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Certificate of Analysis, ROCKLABS Reference Material OxL93, 19 August 2011. Page 1 of 6.
World Leaders in Sample Preparation Equipment,
Automated Systems and Certified Reference Materials
P.O Box 18-142, Glen Innes 1743 Auckland, New Zealand.
P 64 9 634 7696 F 64 9 634 6896 E [email protected]
www.rocklabs.com
Certificate of Analysis
Reference Material OxL93
Recommended Gold Concentration: 5.841 µg/g
95% Confidence Interval: +/- 0.053 µg/g
The above values apply only to product in jars or sachets which have an identification number
within the following range: 248 364 – 250 944.
Prepared and Certified By: Malcolm Smith BSc, FNZIC
Rocklabs Reference Materials
40 Oakford Park Crescent, Greenhithe
Auckland 0632
NEW ZEALAND
Email: [email protected]
Telephone: +64 9 444 3534
Date of Certification: 19 August 2011
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-
mouthed jars that contain 2.5 kg of product. The
contents of some jars may be subsequently
repacked into sealed polyethylene sachets.
Origin of Reference Material: Basalt and feldspar minerals with minor
quantities of finely divided gold-containing
minerals that have been screened to ensure there
is no gold nugget effect.
Supplier of Reference Material: ROCKLABS Ltd
P O Box 18 142
Glen Innes
Auckland 1743
NEW ZEALAND
Email: [email protected]
Website: www.rocklabs.com
Certificate of Analysis, ROCKLABS Reference Material OxL93, 19 August 2011. Page 2 of 6.
Description: The reference material is a light grey powder that has been
well mixed and a homogeneity test carried out after the entire
batch was packaged into wide-mouthed jars. There is no soil
component. The product contains crystalline quartz and
therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values)
%
SiO2 58.70
Al2O3 17.16
Na2O 4.92
K2O 5.25
CaO 3.67
MgO 3.34
TiO2 0.95
MnO 0.06
P2O5 0.25
Fe2O3 4.89
L O I 0.35
Intended Use: This reference material is designed to be included with every
batch of samples analysed and the results plotted for quality
monitoring and assessment purposes.
Stability: The container (jar or sachet) and its contents should not be
heated to temperatures higher than 50 °C. The reference
material is stable, with weight changes of less than 0.5 % at
extremes of naturally occurring temperature and humidity
conditions.
Method of Preparation: Pulverized basalt rock and feldspar minerals were blended
with finely pulverized and screened, gold-containing
minerals. Once the powders were uniformly mixed the
composite was placed into 2581 wide-mouthed jars, each
bearing a unique number. 54 jars were randomly selected
from the packaging run and material from these jars was used
for both homogeneity and consensus testing.
Certificate of Analysis, ROCKLABS Reference Material OxL93, 19 August 2011. Page 3 of 6.
Homogeneity Assessment:
An independent laboratory carried out gold analysis by fire assay of 30 g portions,
using a gravimetric finish. Steps were taken to minimize laboratory method variation
in order to better detect any variation in the candidate reference material.
The contents of six randomly selected jars were compacted by vibration (to simulate
the effect of freighting) and five samples removed successively from top to bottom
from each jar. In addition, five samples were removed from the last jar in the series.
A sample was also removed from the top of each of the 54 jars randomly selected
from the 2581 jars in the batch. The results of analysis of the 89 samples (randomly
ordered and then consecutively numbered before being sent to the laboratory)
produced a relative standard deviation of 0.6 %.
Analytical Methodology:
Once homogeneity had been established, two sub-samples were submitted to a
number of well-recognized laboratories in order to assign a gold value by consensus
testing. The sub-samples were drawn from the 54 randomly selected jars and each
laboratory received samples from two different jars. Indicative concentration ranges
were given. All laboratories used fire assay for the gold analysis, with most using an
instrument finish and 14 using a gravimetric finish.
Calculation of Certified Value:
Results for gold were returned from 44 laboratories. Statistical analysis to identify
outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO
5725-2: 1994. Assessment of each laboratory’s performance was carried out on the
basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1.
Details of the criteria used in these examinations are available on request. As a result
of these statistical analyses, five sets of results were excluded for the purpose of
assigning a gold concentration value to this reference material. A recommended
value was thus calculated from the average of the remaining n = 39 sets of replicate
results. The 95 % confidence interval was estimated using the formula:-
X ± ts/√n
(where X is the estimated average, s is the estimated standard deviation of the
laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-
1 degrees of freedom). The recommended value is provided at the beginning of the
certificate in µg/g (ppm) units. A summary of the results used to calculate the
recommended value is listed on page 4 and the names of the laboratories that
submitted results are listed on page 5. The results are listed in increasing order of the
individual laboratory averages.
Statistical analysis of the consensus test results has been carried out by independent
statistician, Tim Ball.
Certificate of Analysis, ROCKLABS Reference Material OxL93, 19 August 2011. Page 4 of 6.
Summary of Results Used to Calculate Gold Value (Listed in increasing order of individual laboratory averages)
Gold (ppm)
Sample 1 Sample 2 Average
5.289 5.744 5.517
5.506 5.589 5.548
5.68 5.43 5.555
5.54 5.60 5.570
5.66 5.62 5.640
5.727 5.649 5.688
5.54 5.86 5.700
5.73 5.68 5.705
5.78 5.64 5.710
5.642 5.840 5.741
5.79 5.73 5.760
5.726 5.811 5.769
5.743 5.800 5.772
5.73 5.82 5.775
5.66 5.94 5.800
5.850 5.811 5.831
5.815 5.850 5.833
5.85 5.83 5.840
5.850 5.833 5.842
5.884 5.801 5.843
5.84 5.86 5.850
5.885 5.825 5.855
5.87 5.84 5.855
5.83 5.89 5.860
5.87 5.88 5.875
5.94 5.89 5.915
5.91 5.92 5.915
5.947 5.884 5.916
5.93 5.96 5.945
5.940 5.99 5.965
5.94 6.00 5.970
5.94 6.00 5.970
5.965 5.990 5.978
5.95 6.09 6.020
6.04 6.00 6.020
6.025 6.020 6.023
6.02 6.03 6.025
6.04 6.06 6.050
6.49 6.19 6.340
Average of 39 sets = 5.841 ppm
Standard deviation of 39 sets = 0.164 ppm
Relative standard deviation = 2.8 %
95% Confidence interval for average = 0.053 ppm
Note: this standard deviation should not be
used as a basis to set control limits when
plotting results from an individual laboratory.
Certificate of Analysis, ROCKLABS Reference Material OxL93, 19 August 2011. Page 5 of 6.
Participating Laboratories
Australia ALS Minerals, Kalgoorlie
ALS Minerals, Orange
ALS Minerals, Perth
ALS Minerals, Townsville
Amdel – Bureau Veritas, Adelaide
Amdel – Bureau Veritas, Kalgoorlie
Genalysis Laboratory Services, Perth
Independent Assay Laboratories, Perth
SGS Minerals Services, Perth
Standard and Reference, Perth
Ultra Trace – Bureau Veritas, Perth
Burkina Faso ALS Minerals, Burkina Faso
Semafo Burkina Faso S.A.
Canada Acme Analytical Laboratories, Vancouver
ALS Minerals, Val d’Or
ALS Minerals, Vancouver
Bourlamaque Assay Laboratories, Quebec
Loring Laboratories (Alberta) Ltd, Calgary
SGS Minerals Services, Vancouver
SGS Minerals Services, Lakefield
Techni-Lab S.G.B., Québec
TSL Laboratories Inc, Saskatoon
Chile Acme Analytical Laboratories, Santiago
ALS Minerals, La Serena
Côte d’Ivoire Bureau Veritas Mineral Laboratories, Abidjan
Ireland OMAC Laboratories
Kyrgyz Republic Stewart Assay and Environmental Laboratories LLC, Kara-Balta
Mali ALS Minerals, Bamako
New Zealand SGS Minerals Services, Otago
SGS Minerals Services, Waihi
Peru ALS Minerals, Lima
Inspectorate Services Perú S.A.C., Callao
Minera Yanacocha SRL – Newmont, Lima
Russia Irgiredmet Analytical Centre, Irkutsk
South Africa ALS Minerals, Johannesburg
AngloGold Ashanti, Vaal River Chemical Laboratory
Goldfields West Wits Analytical Laboratory
Performance Laboratories, Randfontein
SGS South Africa (Pty) Ltd, Johannesburg
United Kingdom Inspectorate International, Essex
USA ALS Minerals, Reno
Barrick Goldstrike – Met Services
Newmont Mining Corporation, Carlin Laboratory
Zimbabwe Performance Laboratories, Harare
Certificate of Analysis, ROCKLABS Reference Material Ox
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis and analyze for total gold by normal
procedure. Homogeneity testing has shown that consistent results
when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
content of the reference material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the
has been in estimating the declared value. It
laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how
different an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use i
leads to many apparent out-of
testing, or of the reference material itself.
A much better way of determining the laboratory performance when analysing the
reference material is to accumula
control chart. The appropriate centre line and control limits for this chart should be based
on the average level and variability exhibited in the laboratory’s
provide a clear picture of the long
process, providing good clues as to the causes of any problems. To help our customers do
this, we can provide a free Excel template that will produce sensible graphs, with
intelligently chosen limits, from the customer’s own data.
Legal Notice:
This certificate and the reference material described in it have been prepared with due
and attention. However ROCKLABS Ltd,
no liability for any decisions or actions taken following the use of the reference material.
References:
For further information on the preparation and validation of this reference material please
contact Malcolm Smith.
Certifying Officer
M G Smith BSc, FNZIC
ROCKLABS Reference Material OxL93, 19 August 2011
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis and analyze for total gold by normal
procedure. Homogeneity testing has shown that consistent results are obtainable for gold
when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
rence material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the
has been in estimating the declared value. It does not reflect the variability any particular
laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how
t an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use i
of-control points, leading to doubts about the laboratory’s
testing, or of the reference material itself.
A much better way of determining the laboratory performance when analysing the
reference material is to accumulate a history of the test results obtained, and plot them on a
control chart. The appropriate centre line and control limits for this chart should be based
on the average level and variability exhibited in the laboratory’s own
a clear picture of the long-term stability or otherwise of the laboratory testing
providing good clues as to the causes of any problems. To help our customers do
we can provide a free Excel template that will produce sensible graphs, with
telligently chosen limits, from the customer’s own data.
This certificate and the reference material described in it have been prepared with due
CKLABS Ltd, Scott Technology Ltd and Tim Ball Ltd accept
no liability for any decisions or actions taken following the use of the reference material.
For further information on the preparation and validation of this reference material please
Independent Statistician
Tim Ball BSc (Hons)
1. Page 6 of 6.
Weigh out quantity usually used for analysis and analyze for total gold by normal
are obtainable for gold
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
rence material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the trial
reflect the variability any particular
Some users in the past have misinterpreted this confidence interval as a guide as to how
t an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use inevitably
control points, leading to doubts about the laboratory’s
A much better way of determining the laboratory performance when analysing the
te a history of the test results obtained, and plot them on a
control chart. The appropriate centre line and control limits for this chart should be based
own data. This chart will
term stability or otherwise of the laboratory testing
providing good clues as to the causes of any problems. To help our customers do
we can provide a free Excel template that will produce sensible graphs, with
This certificate and the reference material described in it have been prepared with due care
and Tim Ball Ltd accept
no liability for any decisions or actions taken following the use of the reference material.
For further information on the preparation and validation of this reference material please
Independent Statistician
Certificate of Analysis, ROCKLABS Reference Material OxL34, 26 September 2003. Page 1 of 1.
Certificate of Analysis
Reference Material OxL34
Recommended Gold Concentration: 5.758 µg/g 95% Confidence Interval: +/- 0.071 µg/g
The above values apply only to product in jars or sachets which have an identification number within the following range: The number range is not published on the website
Prepared and Certified By: Malcolm Smith BSc, FNZIC Malcolm Smith Reference Materials Ltd 2 Morriggia Place Auckland 10 NEW ZEALAND Telephone: +64 9 444 3534 Telefax: +64 9 444 7739 Email: [email protected]
Date of Certification: 26 September 2003
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-mouthed jars that contain 2.5kg of product. The contents of some jars may be subsequently repacked into sealed polyethylene sachets.
Origin of Reference Material: Feldspars with minor quantities of finely divided gold-containing minerals that have been screened to ensure there is no gold nugget effect.
Supplier of Reference Material: ROCKLABS Ltd P O Box 18 142 Auckland NEW ZEALAND Email: [email protected] Telephone: +64 9 634 7696 Telefax: +64 9 634 6896
Certificate of Analysis, ROCKLABS Reference Material OxL34, 26 September 2003. Page 2 of 2.
Description: The component minerals have been well mixed and a homogeneity test carried out after the entire batch was packaged into wide-mouthed jars to ascertain that the gold is evenly distributed throughout the reference material. There is no soil component. The product contains crystalline quartz and therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values) % SiO2 67.67
Al2O3 19.20
Na2O 10.66
K2O 0.71
CaO 0.29
MgO 0.10
TiO2 0.04
MnO <0.01
P2O5 0.08
Fe2O3 0.55
L O I 0.34
Intended Use: This reference material is designed to be included with every batch of samples analysed and the results plotted for quality monitoring purposes.
Stability: The container (jar or sachet) and its contents should not be heated to temperatures higher than 50 °C. The reference material is stable, with weight changes of less than 0.5% at extremes of naturally occurring temperature and humidity conditions.
Instructions for Use: Weigh out quantity usually used for analysis and analyze for total gold by normal procedure. Homogeneity testing has shown that consistent results are obtainable for gold when 30g portions are taken for analysis. Homogeneity cannot be guaranteed if smaller weights are taken for analysis.
Method of Preparation: Pulverized feldspar minerals were blended with finely pulverized and screened, gold-containing minerals. Once the powders were uniformly mixed the composite was placed into 748 wide-mouthed jars, each bearing a unique number. 30 jars were randomly selected from the packaging run and material from these jars was used for both homogeneity and consensus testing.
Certificate of Analysis, ROCKLABS Reference Material OxL34, 26 September 2003. Page 3 of 3.
Homogeneity Assessment: An independent laboratory carried out all gold analyses by fire assay of 30g portions, using a gravimetric finish with a balance capable of reading to one microgram. Steps were taken to minimize laboratory method variation in order to better detect any variation in the reference material. Homogeneity Assessment Prior to Packaging 30 samples were removed at regular intervals from the prepared candidate reference material prior to packaging into 2.5 kg jars. The results of analysis of the 30 samples produced a coefficient of variation of 0.6%. Homogeneity Assessment After Packaging The contents of three randomly selected jars were compacted by vibration (to simulate the effect of freighting) and five samples removed successively from top to bottom from each of the three jars. In addition, five samples were removed from the last jar in the series. 30 samples were removed from the top of 30 jars randomly selected from the 748 jars in the batch. The results of analysis of the 50 samples produced a coefficient of variation of 0.6%. As the homogeneity testing was carried out using 30g analytical portions, the same degree of homogeneity cannot be guaranteed if smaller weights are taken for analysis.
Analytical Methodology: Once homogeneity had been established, two sub-samples were submitted to a number of well-recognized laboratories in order to assign a gold value by consensus testing. The sub-samples were drawn from the 30 randomly selected jars and each laboratory received samples from two different jars. Indicative concentration ranges were given. Two laboratories used neutron activation and the remainder used fire assay for gold analysis.
Calculation of Certified Value:
30 sets of results were returned from 29 laboratories. Assessment of each laboratory’s performance was carried out on the basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1. Statistical analysis to identify outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994. Details of the criteria used in these examinations are available on request. As a result of these statistical analyses, five sets of results were excluded for the purpose of assigning a gold concentration value to this reference material. A recommended value was thus calculated from the average of the remaining n = 25 sets of replicate results. The 95% confidence interval was estimated using the formula:-
X ± ts/�n (where X is the estimated average, s is the estimated standard deviation of the laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-1 degrees of freedom). The recommended value is provided at the beginning of the certificate in µg/g (ppm) units. A summary of the results used to calculate the recommended value is listed on page 4 and the names of the laboratories that submitted results are listed on page 5.
Certificate of Analysis, ROCKLABS Reference Material OxL34, 26 September 2003. Page 4 of 4.
Legal Notice: This certificate and the reference material described in it have been prepared with due care and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the reference material.
Summary of Results Used to Calculate Gold Value (not related to order of laboratories listed on page 5)
Statistical analysis of both homogeneity and consensus test results has been carried out by an independent statistician.
Gold (ppm)Sample 1 Sample 2 Average
5.350 5.175 5.2635.67 5.33 5.5005.68 5.46 5.5705.58 5.58 5.5805.60 5.59 5.5955.64 5.73 5.6855.6 5.8 5.70
5.70 5.74 5.7205.64 5.86 5.7505.77 5.73 5.7505.734 5.783 5.7595.79 5.75 5.7705.82 5.72 5.7705.65 5.90 5.7755.79 5.79 5.7905.740 5.865 5.8035.820 5.791 5.8065.82 5.80 5.8105.80 5.82 5.8105.89 5.86 5.8755.90 5.91 5.9055.972 5.866 5.9195.91 5.95 5.9305.96 5.97 5.9656.15 6.15 6.150
Average of 25 sets = 5.758 ppmStandard deviation of 25 sets = 0.173 ppm
Coefficient of variation = 3.0 %95% Confidence interval for average = 0.071 ppm
Certificate of Analysis, ROCKLABS Reference Material OxL34, 26 September 2003. Page 5 of 5.
Participating Laboratories Australia Amdel, Adelaide Amdel, Perth
Amdel, Kalgoorlie Becquerel Laboratories, Lucas Heights Genalysis Laboratory Services Pty Ltd, Perth SGS Analabs, Perth SGS Analabs, Townsville Standard and Reference Laboratories, Perth
Brazil Lakefield Geosol Limitada
Canada Acme Analytical Laboratories Ltd, British Columbia Activation Laboratories Ltd, Ontario ALS Chemex, British Columbia ALS Chemex Chimitec, Quebec Bourlamaque Assay Laboratories Ltd, Quebec SGS Lakefield Research Limited, Ontario
SGS XRAL Laboratories, Ontario
Ireland OMAC Laboratories Ltd
New Zealand Amdel New Zealand Ltd, Otago SGS New Zealand Ltd, Waihi
Russia Irgiredmet, Irkutsk Magadangeologia, Magadan Tsnigri, Moscow
South Africa Anglo American Research Laboratories (Pty) Ltd AngloGold, Vaal River AngloGold, West Wits Mintek, Analytical Services Division SGS Lakefield Research Africa (Pty) Ltd
United States of America ALS Chemex, Nevada Barrick Goldstrike Mines Inc, Nevada Newmont Mining Corporation, Nevada
References: For further information on the preparation and validation of this reference material please contact Malcolm Smith.
Certifying Officer Independent Statistician
M G Smith BSc, FNZIC Tim Ball BSc (Hons)
Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 1 of 6.
P.O Box 18-142, Glen Innes 1743 Auckland, New Zealand.
P 64 9 634 7696 F 64 9 634 6896 E [email protected]
www.rocklabs.com
World Leaders in Sample Preparation Equipment,
Automated Systems and Certified Reference Materials
Certificate of Analysis
Reference Material OxL135
Recommended Gold Concentration: 5.587 µg/g
95% Confidence Interval: +/- 0.036 µg/g
The above values apply only to product in jars or sachets which have an identification number
within the following range: 412 354– 413 207.
Prepared and Certified By: Brett Coombridge, M.Phil. Chemistry
Rocklabs Reference Materials
P.O. Box 316056
Wairau Valley Post Centre
Auckland 0760
NEW ZEALAND
Email: [email protected]
Telephone: +64 9 444 3534
Date of Certification: 18 December 2014
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-
mouthed jars that contain 2.5 kg of product. The
contents of some jars may be subsequently
repacked into sealed polyethylene sachets.
Origin of Reference Material: Basalt and feldspar minerals with minor
quantities of finely divided gold-containing
minerals that have been screened to ensure there
is no gold nugget effect.
Supplier of Reference Material: ROCKLABS
P O Box 18 142
Glen Innes
Auckland 1743
NEW ZEALAND
Email: [email protected]
Website: www.rocklabs.com
Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 2 of 6
Description: The reference material is a light grey powder that has been
well mixed and a homogeneity test carried out after the entire
batch was packaged into wide-mouthed jars. There is no soil
component. The product contains crystalline quartz and
therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values)
%
SiO2 58.86
Al2O3 16.91
Na2O 4.78
K2O 5.32
CaO 3.71
MgO 3.43
TiO2 0.99
MnO 0.06
P2O5 0.26
Fe2O3 5.21
L O I 0.28
Intended Use: This reference material is designed to be included with every
batch of samples analysed and the results plotted for quality
monitoring and assessment purposes.
Stability: The container (jar or sachet) should not be heated to
temperatures higher than 50 °C. The reference material is
stable, with weight changes of less than 0.5 % at extremes of
naturally occurring temperature and humidity conditions.
Method of Preparation: Pulverized basalt rock and feldspar minerals were blended
with finely pulverized and screened gold-containing minerals.
Once the powders were uniformly mixed the composite was
placed into 854 wide-mouthed jars, each bearing a unique
number. 24 jars were randomly selected from the packaging
run and material from these jars was used for both
homogeneity and consensus testing.
Homogeneity Assessment:
Sampling was performed by Rocklabs Reference Materials and an independent
laboratory carried out gold analysis by fire assay of 30 g portions, using a gravimetric
finish. Steps were taken to minimize laboratory method variation in order to better
detect any variation in the candidate reference material.
Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 3 of 6
Homogeneity: A sample was removed from the top of each of the 24 jars randomly
selected from the 854 jars in the batch. The results of analysis of the 24 samples
(randomly ordered then consecutively numbered before being sent to the laboratory)
indicated 4 results were anomalously low. Analysis of the slags and crucibles related
to these sample showed that excessive gold had been retained, and so the original
reported results for these samples were discarded. The test results of the remaining
20 samples produced a relative standard deviation of 0.9 %.
Settling: The contents of 3 randomly selected jars were compacted by vibration (to
simulate the effect of freighting) and 5 samples were removed successively from top
to bottom from each jar. In addition, 5 samples were removed from the last jar in the
series. No top to bottom gradation in the gold values was observed neither was there
a significant difference between the last jar and the other jars.
Analytical Methodology:
Once homogeneity had been established, two sub-samples were submitted to a
number of well-recognized laboratories in order to assign a gold value by consensus
testing. The sub-samples were drawn from 24 randomly selected jars and each
laboratory received samples from two different jars.
The samples were analysed for gold by all participating laboratories using fire assay
followed by either gravimetric or instrument finish (AAS or ICP). Indicative
concentration ranges were provided. The amount of sample used in the analyses
varied between laboratories (range 10 - 50g).
Calculation of Certified Value:
The 53 participating laboratories each returned replicate gold results using one finish
method for both samples. Statistical analysis to identify outliers was carried out
using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994. Assessment
of each laboratory’s performance was carried out on the basis of z-scores, partly
based on the concept described in ISO/IEC Guide 43-1. Details of the criteria used
in these examinations are available on request. As a result of these statistical
analyses, 6 sets of results were excluded for the purpose of assigning a gold
concentration value to this reference material. A recommended value was thus
calculated from the average of the remaining n = 47 sets of replicate results. The
95% confidence interval was estimated using the formula:-
X ts/√n
(where X is the estimated average, s is the estimated standard deviation of the
laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-
1 degrees of freedom). The recommended value is provided at the beginning of the
certificate in µg/g (ppm) units. A summary of the results used to calculate the
recommended value is listed on page 4 and the names of the laboratories that
submitted results are listed on page 5. The results are listed in increasing order of the
individual laboratory averages.
Statistical analysis of the consensus test results has been carried out by independent
statistician, Tim Ball.
Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 4 of 6
Summary of Results Used to Calculate Gold Value (Listed in increasing order of individual laboratory averages)
Note: Neither the Standard deviation nor the Confidence interval should be
used as a basis to set control limits when plotting individual laboratory results.
See notes under "Instructions and Recommendations for Use" (pg 6)
Sample 1 Sample 2 Set Average5.315 5.365 5.340
5.195 5.510 5.353
5.459 5.353 5.406
5.35 5.55 5.450
5.535 5.370 5.453
5.580 5.365 5.473
5.505 5.445 5.475
5.503 5.473 5.488
5.478 5.500 5.489
5.47 5.51 5.490
5.56 5.43 5.495
5.488 5.507 5.498
5.522 5.530 5.526
5.554 5.499 5.527
5.503 5.555 5.529
5.52 5.54 5.530
5.53 5.53 5.530
5.64 5.43 5.535
5.53 5.54 5.535
5.51 5.57 5.540
5.48 5.60 5.540
5.523 5.565 5.544
5.53 5.56 5.545
5.558 5.558 5.558
5.53 5.59 5.560
5.540 5.595 5.568
5.47 5.68 5.575
5.582 5.584 5.583
5.457 5.749 5.603
5.63 5.58 5.605
5.61 5.61 5.610
5.68 5.56 5.620
5.60 5.70 5.650
5.71 5.59 5.650
5.615 5.742 5.679
5.743 5.636 5.690
5.633 5.752 5.693
5.68 5.76 5.720
5.745 5.710 5.728
5.858 5.614 5.736
5.718 5.767 5.743
5.615 5.885 5.750
5.816 5.692 5.754
5.77 5.74 5.755
5.69 5.84 5.765
5.76 5.83 5.795
6.01 5.82 5.915
Average of 47 sets = 5.587 ppm
Standard deviation of 47 sets = 0.121 ppmRelative standard deviation = 2.2 %95% Confidence interval for average: = +/- 0.036 ppm
Gold (ppm)
Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 5 of 6
Participating Laboratories
Australia ALS Minerals, Burnie
ALS Minerals, Kalgoorlie
ALS Minerals, Orange
ALS Minerals, Perth
ALS Minerals, Townsville
Bureau Veritas Amdel, Adelaide
Bureau Veritas Amdel, Kalgoorlie
Intertek Genalysis Laboratory Services, Perth
Burkina Faso ALS Minerals, Burkina Faso
SEMAFO Burkina Faso S.A.
Canada Acme Analytical Laboratories, Vancouver
ALS Minerals, Val-d’Or
ALS Minerals, Vancouver
Bourlamaque, Quebec
Loring Laboratories (Alberta) Ltd, Calgary
SGS Minerals Services, Lakefield, Ontario
SGS Minerals Services, Vancouver
Techni-Lab S.G.B. Abitibi Inc/Actlabs, Val d’Or
Techni-Lab S.G.B. Abitibi Inc/Actlabs, Ste-Germaine-Boule
TSL Laboratories Inc, Saskatoon
Chile Acme Analytical Laboratories, Santiago
Côte d’Ivoire Bureau Veritas Mineral Laboratories, Abidjan
Ghana ALS Minerals, Kumasi
Performance Laboratories, Obuasi AngloGold
Ireland ALS Minerals, Loughrea
Kyrgyz Republic Stewart Assay and Environmental Laboratories LLC, Kara-Balta
Laos ALS Geochemistry, Vientiane
Mali ALS Minerals, Bamako
Mongolia ALS Minerals, Ulaanbaatar
Namibia Bureau Veritas- Mineral Laboratories, Swakopmund
New Zealand SGS New Zealand Ltd, Otago
SGS New Zealand Ltd, Reefton
SGS New Zealand Ltd, Waihi
Peru ALS Minerals, Lima
Inspectorate Services Perú S.A.C., Callao
Minera Yanacocha SRL – Newmont, Lima
Romania ALS Minerals, Rosia Montana
Russia Irgiredmet Analytical Centre, Irkutsk
South Africa Acme, Inspectorate M & M, Rustenburg
ALS Minerals, Edenvale
SibanyeGold, Driefontein Operations
Performance Laboratories, Allanridge
Performance Laboratories, Barberton
Performance Laboratories, Randfontein
Turkey Acme Analitik Laboratuar Hizmetleri Ltd, Sirketi
ALS Minerals, Izmir
USA ALS Minerals, Reno
Barrick Goldstrike – Met Services, Nevada
Inspectorate, Sparks
Newmont Mining Corporation, Carlin
Newmont Mining Corporation, Lone Tree
Newmont Mining Corporation, Twin Creeks
Zimbabwe Performance Laboratories, Ruwa
Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 6 of 6
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis, and analyse for total gold by normal
procedure. Homogeneity testing has shown that consistent results are obtainable for gold
when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
content of the reference material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the trial
has been in estimating the declared value. It does not reflect the variability any particular
laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how
different an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use inevitably
leads to many apparent out-of-control points, leading to doubts about the laboratory’s
testing, or of the reference material itself.
A much better way of determining the laboratory performance when analysing the
reference material is to accumulate a history of the test results obtained, and plot them on a
control chart. The appropriate centre line and control limits for this chart should be based
on the average level and variability exhibited in the laboratory’s own data. This chart will
provide a clear picture of the long-term stability or otherwise of the laboratory testing
process, providing good clues as to the causes of any problems. To help our customers do
this, we can provide a free Excel template that will produce sensible graphs, with
intelligently chosen limits, from the customer’s own data.
Legal Notice:
This certificate and the reference material described in it have been prepared with due care
and attention. However ROCKLABS Ltd, Scott Technology Ltd and Tim Ball Ltd accept
no liability for any decisions or actions taken following the use of the reference material.
References:
For further information on the preparation and validation of this reference material please
contact Malcolm Smith.
Certifying Officer Independent Statistician
Brett Coombridge (M.Phil. Chemistry) Tim Ball BSc (Hons)
Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 1 of 6.
161 Neilson Street, Auckland, New Zealand Email: [email protected]
Tel: +64 9 634 7696 Fax: +64 9 634 6896 Website: www.rocklabs.com Certificate of Analysis
Reference Material OxL63
Recommended Gold Concentration: 5.865 µg/g
95% Confidence Interval: +/- 0.055 µg/g
The above values apply only to product in jars or sachets which have an identification number
within the following range: 147 243 – 148 780.
Prepared and Certified By: Malcolm Smith BSc, FNZIC
Malcolm Smith Reference Materials Ltd
40 Oakford Park Crescent, Greenhithe
North Shore City 0632
NEW ZEALAND
Email: [email protected]
Telephone: +64 9 444 3534
Date of Certification: 23 October 2007
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-
mouthed jars that contain 2.5 kg of product. The
contents of some jars may be subsequently
repacked into sealed polyethylene sachets.
Origin of Reference Material: Basalt and feldspar minerals with minor
quantities of finely divided gold-containing
minerals that have been screened to ensure there
is no gold nugget effect.
Supplier of Reference Material: ROCKLABS Ltd
P O Box 18 142
Auckland
NEW ZEALAND
Email: [email protected]
Website: www.rocklabs.com
Telephone: +64 9 634 7696
Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 2 of 6.
Description: The reference material is a light grey powder that has been
well mixed and a homogeneity test carried out after the entire
batch was packaged into wide-mouthed jars. There is no soil
component. The product contains crystalline quartz and
therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values)
%
SiO2 62.28
Al2O3 17.57
Na2O 6.85
K2O 3.36
CaO 2.40
MgO 2.46
TiO2 0.70
MnO 0.05
P2O5 0.23
Fe2O3 3.74
L O I 0.31
Intended Use: This reference material is designed to be included with every
batch of samples analysed and the results plotted for quality
monitoring purposes.
Stability: The container (jar or sachet) and its contents should not be
heated to temperatures higher than 50 °C. The reference
material is stable, with weight changes of less than 0.5 % at
extremes of naturally occurring temperature and humidity
conditions.
Method of Preparation: Pulverized basalt rock and feldspar minerals were blended
with finely pulverized and screened, gold-containing
minerals. Once the powders were uniformly mixed the
composite was placed into 1538 wide-mouthed jars, each
bearing a unique number. 48 jars were randomly selected
from the packaging run and material from these jars was used
for both homogeneity and consensus testing.
Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 3 of 6.
Homogeneity Assessment:
An independent laboratory carried out all gold analyses by fire assay of 30 g portions,
using a gravimetric finish. Steps were taken to minimize laboratory method variation
in order to better detect any variation in the candidate reference material.
Homogeneity Assessment After Packaging
The contents of six randomly selected jars were compacted by vibration (to simulate
the effect of freighting) and five samples removed successively from top to bottom
from each jar. In addition, five samples were removed from the last jar in the series.
A sample was also removed from the top of each of the 48 jars randomly selected
from the 1538 jars in the batch. The results of analysis of the 83 samples (randomly
ordered and then consecutively numbered before being sent to the laboratory)
produced a coefficient of variation of 0.9 %.
Analytical Methodology:
Once homogeneity had been established, two sub-samples were submitted to a
number of well-recognized laboratories in order to assign a gold value by consensus
testing. The sub-samples were drawn from the 48 randomly selected jars and each
laboratory received samples from two different jars. Indicative concentration ranges
were given. All laboratories used fire assay for the gold analysis.
Calculation of Certified Value:
Results for gold were returned from 31 laboratories. Statistical analysis to identify
outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO
5725-2: 1994. Assessment of each laboratory’s performance was carried out on the
basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1.
Details of the criteria used in these examinations are available on request. As a result
of these statistical analyses, three sets of results were excluded for the purpose of
assigning a gold concentration value to this reference material. A recommended
value was thus calculated from the average of the remaining n = 28 sets of replicate
results. The 95 % confidence interval was estimated using the formula:-
X ± ts/√n
(where X is the estimated average, s is the estimated standard deviation of the
laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-
1 degrees of freedom). The recommended value is provided at the beginning of the
certificate in µg/g (ppm) units. A summary of the results used to calculate the
recommended value is listed on page 4 and the names of the laboratories that
submitted results are listed on page 5.
Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 4 of 6.
Summary of Results Used to Calculate Gold Value (not related to order of laboratories listed on page 5)
Gold (ppm)
Sample 1 Sample 2 Average
5.25 5.64 5.445
5.561 5.645 5.6030
5.42 5.84 5.630
5.62 5.76 5.690
5.73 5.80 5.765
5.74 5.79 5.765
5.81 5.80 5.805
5.825 5.795 5.8100
5.73 5.91 5.820
5.84 5.82 5.830
5.956 5.735 5.8455
5.850 5.880 5.8650
5.896 5.853 5.8745
5.85 5.90 5.875
5.846 5.949 5.8975
5.849 6.025 5.9370
5.97 5.92 5.945
5.90 5.99 5.945
5.967 5.933 5.9500
5.94 5.97 5.955
5.95 5.96 5.955
6.034 5.897 5.9655
5.985 5.959 5.9720
5.94 6.04 5.990
6.00 6.00 6.000
5.97 6.04 6.005
6.034 5.983 6.0085
6.015 6.105 6.0600
Average of 28 sets = 5.865 ppm
Standard deviation of 28 sets = 0.141 ppm
Coefficient of variation = 2.4 %
95% Confidence interval for average = 0.055 ppm
Note: this standard deviation should not be used as
a basis to set control limits when plotting results
from an individual laboratory.
Statistical analysis of both homogeneity and consensus test results has been carried
out by independent statistician, Tim Ball.
Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 5 of 6.
Participating Laboratories
Australia ALS Chemex, Perth
Amdel Ltd, Adelaide
Amdel Laboratories Ltd, Perth
Amdel Laboratories Ltd, Kalgoorlie
Genalysis Laboratory Services Pty Ltd, Perth
SGS Welshpool Minerals, Perth
SGS Townsville Minerals, Townsville
Standard and Reference Laboratories, Perth
Ultra Trace Analytical Laboratories, Perth
Canada ALS Chemex, British Columbia
ALS Chemex, Quebec
Assayers Canada, British Columbia
Bourlamaque Assay Laboratories Ltd, Quebec
International Plasma Labs Ltd, British Columbia
Loring Laboratories, Alberta
SGS Minerals Services, Ontario
TSL Laboratories Inc, Saskatchewan
Chile ACME Analytical Laboratories Ltda
Kyrgyzstan Alex Stewart Assay and Environmental Laboratories Ltd
New Zealand SGS Minerals, Waihi
Peru Minera Yanacocha SRL – Newmont
Russia Irgiredmet, Irkutsk
Russian Academy of Science, Karelia
South Africa Anglo Research
MINTEK: Analytical Services Division
SGS Lakefield Research Africa
United States of America ALS Chemex, Nevada
Barrick Goldstrike Mines Inc, Nevada
Newmont Mining Corporation, Carlin Laboratory
Newmont Mining Corporation, Lone Tree Laboratory
Newmont Mining Corporation, Twin Creeks Laboratory
Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 6 of 6.
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis and analyze for total gold by normal
procedure. Homogeneity testing has shown that consistent results are obtainable for gold
when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
content of the reference material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the trial
has been in estimating the declared value. It does not reflect the variability any particular
laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how
different an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use inevitably
leads to many apparent out-of-control points, leading to doubts about the laboratory’s
testing, or of the reference material itself.
A much better way of determining the laboratory performance when analysing the
reference material is to accumulate a history of the test results obtained, and plot them on a
control chart. The appropriate centre line and control limits for this chart should be based
on the average level and variability exhibited in the laboratory’s own data. This chart will
provide a clear picture of the long-term stability or otherwise of the laboratory testing
process, providing good clues as to the causes of any problems. To help our customers do
this more simply for themselves, we can provide a free Excel template that will produce
sensible graphs, with intelligently chosen limits, from the customer’s own data.
Legal Notice:
This certificate and the reference material described in it have been prepared with due care
and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and
Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the
reference material.
References:
For further information on the preparation and validation of this reference material please
contact Malcolm Smith.
Certifying Officer Independent Statistician
M G Smith BSc, FNZIC Tim Ball BSc (Hons)
Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 1 of 6.
Certificate of Analysis
Reference Material OxL78
Recommended Gold Concentration: 5.876 µg/g
95% Confidence Interval: +/- 0.053 µg/g
The above values apply only to product in jars or sachets which have an identification number
within the following range: 197 841 – 199 212.
Prepared and Certified By: Malcolm Smith BSc, FNZIC
Malcolm Smith Reference Materials Ltd
40 Oakford Park Crescent, Greenhithe
North Shore City 0632
NEW ZEALAND
Email: [email protected]
Telephone: +64 9 444 3534
Date of Certification: 19 June 2009
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-
mouthed jars that contain 2.5 kg of product. The
contents of some jars may be subsequently
repacked into sealed polyethylene sachets.
Origin of Reference Material: Basalt and feldspar minerals with minor
quantities of finely divided gold-containing
minerals that have been screened to ensure there
is no gold nugget effect.
Supplier of Reference Material: ROCKLABS Ltd
P O Box 18 142
Auckland 1743
NEW ZEALAND
Email: [email protected]
Website: www.rocklabs.com
Telephone: +64 9 634 7696
Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 2 of 6.
Description: The reference material is a light grey powder that has been
well mixed and a homogeneity test carried out after the entire
batch was packaged into wide-mouthed jars. There is no soil
component. The product contains crystalline quartz and
therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values)
%
SiO2 59.34
Al2O3 17.58
Na2O 5.16
K2O 4.96
CaO 3.51
MgO 2.94
TiO2 0.92
MnO 0.07
P2O5 0.24
Fe2O3 4.70
L O I 0.56
Intended Use: This reference material is designed to be included with every
batch of samples analysed and the results plotted for quality
monitoring purposes.
Stability: The container (jar or sachet) and its contents should not be
heated to temperatures higher than 50 °C. The reference
material is stable, with weight changes of less than 0.5 % at
extremes of naturally occurring temperature and humidity
conditions.
Method of Preparation: Pulverized basalt rock and feldspar minerals were blended
with finely pulverized and screened, gold-containing
minerals. Once the powders were uniformly mixed the
composite was placed into 1372 wide-mouthed jars, each
bearing a unique number. 70 jars were randomly selected
from the packaging run and material from these jars was used
for both homogeneity and consensus testing.
Homogeneity Assessment:
An independent laboratory carried out all gold analyses by fire assay of 30 g portions,
using a gravimetric finish. Steps were taken to minimize laboratory method variation
in order to better detect any variation in the candidate reference material.
Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 3 of 6.
Homogeneity Assessment continued:
The contents of five randomly selected jars were compacted by vibration (to simulate
the effect of freighting) and five samples removed successively from top to bottom
from each jar. In addition, five samples were removed from the last jar in the series.
A sample was also removed from the top of each of the 40 jars randomly selected
from the 1372 jars in the batch. The results of analysis of the 70 samples (randomly
ordered and then consecutively numbered before being sent to the laboratory)
produced a relative standard deviation of 1.3 %.
Analytical Methodology:
Once homogeneity had been established, two sub-samples were submitted to a
number of well-recognized laboratories in order to assign a gold value by consensus
testing. The sub-samples were drawn from the 40 randomly selected jars and each
laboratory received samples from two different jars. Indicative concentration ranges
were given. All laboratories used fire assay for the gold analysis, with some using an
instrument finish and some a gravimetric finish.
Calculation of Certified Value:
Results for gold were returned from 40 laboratories. Statistical analysis to identify
outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO
5725-2: 1994. Assessment of each laboratory’s performance was carried out on the
basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1.
Details of the criteria used in these examinations are available on request. As a result
of these statistical analyses, six sets of results were excluded for the purpose of
assigning a gold concentration value to this reference material. A recommended
value was thus calculated from the average of the remaining n = 34 sets of replicate
results. The 95 % confidence interval was estimated using the formula:-
X ± ts/√n
(where X is the estimated average, s is the estimated standard deviation of the
laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-
1 degrees of freedom). The recommended value is provided at the beginning of the
certificate in µg/g (ppm) units. A summary of the results used to calculate the
recommended value is listed on page 4 and the names of the laboratories that
submitted results are listed on page 5. The results are listed in increasing order of the
individual laboratory averages. A code also indicates the method used by the
laboratory. The code starts with the sample weight used (where this is known) and
finishes with either the instrument used (eg AAS or ICP-OES) or gravimetric finish
(indicated by “grav”). Statistical analysis was carried out separately on two groups of
samples – those analysed with an instrument finish and those completed by
gravimetry. There was no significant difference in the calculated gold average for
each group. This applied with outliers included as well as with outliers excluded,
therefore the assigned value was calculated from the combined sets of results.
Statistical analysis of the consensus test results has been carried out by independent
statistician, Tim Ball.
Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 4 of 6.
Summary of Results Used to Calculate Gold Value (Listed in increasing order of individual laboratory averages)
Method Sample 1 Sample 2 Average
30gfa/grav 5.63 5.54 5.585
50gfa/ICP 5.55 5.65 5.600
30gfa/AAS 5.65 5.69 5.670
50gfa/AAS 5.65 5.70 5.675
fa/AAS 5.664 5.703 5.684
20gfa/AAS 5.73 5.66 5.695
15gfa/grav 5.66 5.73 5.695
30gfa/AAS 5.70 5.75 5.725
fa/grav 5.84 5.72 5.780
30gfa/AAS 5.774 5.840 5.807
30gfa/ICP-ES 5.86 5.80 5.830
50gfa/AAS 5.86 5.80 5.830
30gfa/AAS 5.85 5.81 5.830
50gfa/AAS 5.86 5.83 5.845
fa/AAS 5.820 5.875 5.848
30gfa/AAS 5.83 5.90 5.865
fa/grav 5.884 5.884 5.884
30gfa/AAS 5.84 5.94 5.890
30gfa/grav 5.88 5.92 5.900
30gfa/AAS 5.900 5.900 5.900
10gfa/AAS 5.87 5.94 5.905
30gfa/grav 5.95 5.88 5.915
fa/grav 5.874 5.957 5.916
30gfa/AAS 5.984 5.969 5.977
30gfa/grav 5.99 5.97 5.980
15gfa/AAS 5.983 5.983 5.983
30gfa/AAS 6.03 5.96 5.995
30gfa/grav 6.039 5.957 5.998
30gfa/AAS 6.01 6.05 6.030
50gfa/AAS 6.050 6.045 6.048
fa/grav 6.093 6.057 6.075
30gfa/AAS 6.09 6.12 6.105
30gfa/AAS 6.17 6.15 6.160
40gfa/ICP-OES 6.140 6.200 6.170
Average of 34 sets = 5.876 ppm
Standard deviation of 34 sets = 0.153 ppm
Relative standard deviation = 2.6 %
95% Confidence interval for average = 0.053 ppm
Gold (ppm)
Note: this standard deviation should not be used as a basis to set control limits
when plotting results from an individual laboratory.
Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 5 of 6.
Participating Laboratories
Australia ALS Chemex, Kalgoorlie
ALS Chemex, Perth
Amdel Ltd, Adelaide
Amdel Ltd, Kalgoorlie
Genalysis Laboratory Services Pty Ltd, Perth
SGS Australia Pty Ltd, Perth
SGS Australia Pty Ltd, Townsville
Standard and Reference Laboratories, Perth
Ultra Trace Pty Ltd, Perth
Burkina Faso ALS Chemex, Ouagadougou
Canada Accurassay Laboratories, Thunder Bay
Acme Analytical Laboratories Ltd, Vancouver
ALS Chemex, Val d’Or
ALS Chemex, Vancouver
Assayers Canada, Vancouver
Bourlamaque Assay Laboratories Ltd, Val d’Or
International Plasma Labs Ltd, Richmond
Loring Laboratories Ltd, Calgary
SGS Mineral Services, Lakefield
Techni-Lab S.G.B. Abitibi Inc, Quebec
TSL Laboratories Inc, Saskatoon
Chile Acme Analytical Laboratories Ltd, Santiago
Kyrgyzstan Alex Stewart Assay and Environmental Laboratories Ltd, Kara-Balta
Mali ALS Chemex, Bamako
New Zealand Amdel NZ Ltd, Macraes, Otago
Amdel Ltd, Reefton
SGS Minerals, Waihi
Peru ALS Chemex, Lima
Minera Yanacocha SRL – Newmont, Lima
Inspectorate Services Peru S.A.C., Callao
Russia Irgiredmet JSC, Analytical Centre, Irkutsk
South Africa AB Analytical Laboratory Services, Boksburg
Anglo Research, Johannesburg
Performance Laboratories, Randfontein
SGS South Africa (Pty) Ltd, Barberton
SGS South Africa (Pty) Ltd, Southdale
United States of America ALS Chemex, Reno
Barrick Goldstrike Mines Inc, Carlin
Newmont Mining Corporation, Carlin Laboratory
Newmont Mining Corporation, Lone Tree Laboratory
Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 6 of 6.
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis and analyze for total gold by normal
procedure. Homogeneity testing has shown that consistent results are obtainable for gold
when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
content of the reference material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the trial
has been in estimating the declared value. It does not reflect the variability any particular
laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how
different an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use inevitably
leads to many apparent out-of-control points, leading to doubts about the laboratory’s
testing, or of the reference material itself.
A much better way of determining the laboratory performance when analysing the
reference material is to accumulate a history of the test results obtained, and plot them on a
control chart. The appropriate centre line and control limits for this chart should be based
on the average level and variability exhibited in the laboratory’s own data. This chart will
provide a clear picture of the long-term stability or otherwise of the laboratory testing
process, providing good clues as to the causes of any problems. To help our customers do
this more simply for themselves, we can provide a free Excel template that will produce
sensible graphs, with intelligently chosen limits, from the customer’s own data.
Legal Notice:
This certificate and the reference material described in it have been prepared with due care
and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and
Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the
reference material.
References:
For further information on the preparation and validation of this reference material please
contact Malcolm Smith.
Certifying Officer Independent Statistician
M G Smith BSc, FNZIC Tim Ball BSc (Hons)
Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 1 of 6
P.O Box 18-142, Glen Innes 1743 Auckland, New Zealand.
P 64 9 634 7696 F 64 9 634 6896 E [email protected]
www.rocklabs.com
World Leaders in Sample Preparation Equipment,
Automated Systems and Certified Reference Materials
Certificate of Analysis
Reference Material OxL118
Recommended Gold Concentration: 5.828 µg/g
95% Confidence Interval: +/- 0.041 µg/g
The above values apply only to product in jars or sachets which have an identification number
within the following range: 336 813– 340 182.
Prepared and Certified By: Brett Coombridge, M.Phil. Chemistry
Rocklabs Reference Materials
P.O. Box 316056
Wairau Valley Post Centre
Auckland 0760
NEW ZEALAND
Email: [email protected]
Telephone: +64 9 444 3534
Date of Certification: 26 November 2013
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-
mouthed jars that contain 2.5 kg of product. The
contents of some jars may be subsequently
repacked into sealed polyethylene sachets.
Origin of Reference Material: Basalt and feldspar minerals with minor
quantities of finely divided gold-containing
minerals that have been screened to ensure there
is no gold nugget effect.
Supplier of Reference Material: ROCKLABS
P O Box 18 142
Glen Innes
Auckland 1743
NEW ZEALAND
Email: [email protected]
Website: www.rocklabs.com
Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 2 of 6
Description: The reference material is a light grey powder that has been
well mixed and a homogeneity test carried out after the entire
batch was packaged into wide-mouthed jars. There is no soil
component. The product contains crystalline quartz and
therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values)
%
SiO2 59.24
Al2O3 16.73
Na2O 4.33
K2O 6.40
CaO 3.22
MgO 3.24
TiO2 0.88
MnO 0.06
P2O5 0.23
Fe2O3 4.77
L O I 0.19
Intended Use: This reference material is designed to be included with every
batch of samples analysed and the results plotted for quality
monitoring and assessment purposes.
Stability: The container (jar or sachet) should not be heated to
temperatures higher than 50 °C. The reference material is
stable, with weight changes of less than 0.5 % at extremes of
naturally occurring temperature and humidity conditions.
Method of Preparation: Pulverized basalt rock and feldspar minerals were blended
with finely pulverized and screened gold-containing minerals.
Once the powders were uniformly mixed the composite was
placed into 3370 wide-mouthed jars, each bearing a unique
number. 60 jars were randomly selected from the packaging
run and material from these jars was used for both
homogeneity and consensus testing.
Homogeneity Assessment:
Sampling (described below) was performed by Rocklabs Reference Materials and an
independent laboratory carried out gold analysis of the samples by fire assay of 30 g
portions, using a gravimetric finish. Steps were taken to minimize laboratory method
variation to better detect any variation in the candidate reference material.
Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 3 of 6
Homogeneity: A sample was removed from the top of each of the 60 jars randomly
selected from the 3370 jars in the batch. The results of analysis of the 60 samples
(randomly ordered then consecutively numbered before being sent to the laboratory)
produced a relative standard deviation of 1.0%.
Settling: The contents of 6 randomly selected jars were compacted by vibration (to
simulate the effect of freighting) and 5 samples were removed successively from top
to bottom from each jar. In addition, 5 samples were removed and tested from the
last jar in the series. No top to bottom gradation in the gold values was observed
neither was there a significant difference between the last jar and the other jars.
Analytical Methodology:
Once homogeneity had been established, two sub-samples were submitted to a
number of well-recognized laboratories in order to assign a gold value by consensus
testing. The sub-samples were drawn from 60 randomly selected jars and each
laboratory received samples from two different jars.
Participating laboratories analysed the samples by fire assay followed by either
gravimetric or instrument finish (AAS or ICP). Indicative concentration ranges were
provided. Some laboratories analysed the samples twice using both methods. In this
situation both sets of results were presented separately, and included in the statistical
analysis. The amount of sample used in the analyses varied between laboratories
(range 15 - 50g).
Calculation of Certified Value:
As some laboratories returned results for two different methods, 58 sets of gold
results were returned from 54 laboratories. Statistical analysis to identify outliers was
carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994.
Assessment of each laboratory’s performance was carried out on the basis of z-scores,
partly based on the concept described in ISO/IEC Guide 43-1. Details of the criteria
used in these examinations are available on request. As a result of these statistical
analyses, 4 sets of results were excluded for the purpose of assigning a gold
concentration value to this reference material. A recommended value was thus
calculated from the average of the remaining n = 54 sets of replicate results. The
95% confidence interval was estimated using the formula:-
X ts/√n
(where X is the estimated average, s is the estimated standard deviation of the
laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-
1 degrees of freedom). The recommended value is provided at the beginning of the
certificate in µg/g (ppm) units. A summary of the results used to calculate the
recommended value is listed on page 4 and the names of the laboratories that
submitted results are listed on page 5. The results are listed in increasing order of the
individual laboratory averages.
Statistical analysis of the consensus test results has been carried out by independent
statistician, Tim Ball.
Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 4 of 6
Summary of Results Used to Calculate Gold Value (Listed in increasing order of individual laboratory averages)
Note: Neither the Standard deviation nor the Confidence interval should be
used as a basis to set control limits when plotting individual laboratory results.
See notes under "Instructions and Recommendations for Use" (pg 6)
Sample 1 Sample 2 Set Average5.32 5.68 5.5
5.52 5.54 5.53
5.571 5.55 5.5585
5.61 5.54 5.575
5.750 5.448 5.599
5.69 5.52 5.605
5.480 5.785 5.6325
5.62 5.67 5.645
5.49 5.83 5.66
5.725 5.612 5.6685
5.7 5.7 5.7
5.705 5.715 5.71
5.72 5.76 5.74
5.750 5.750 5.75
5.685 5.820 5.7525
5.80 5.71 5.755
5.729 5.782 5.7555
5.69 5.83 5.76
5.758 5.772 5.765
5.80 5.76 5.78
5.890 5.760 5.825
5.8 5.85 5.83
5.93 5.74 5.835
5.844 5.830 5.837
5.865 5.810 5.8375
5.8 5.9 5.84
5.814 5.868 5.841
5.840 5.855 5.8475
5.970 5.735 5.8525
5.84 5.87 5.855
5.890 5.830 5.86
5.861 5.863 5.862
5.78 5.96 5.87
5.88 5.86 5.87
5.89 5.86 5.875
5.78 5.98 5.88
5.871 5.906 5.8885
5.90 5.89 5.895
5.86 5.97 5.915
5.91 5.93 5.92
5.91 5.94 5.925
5.92 5.95 5.935
5.99 5.89 5.94
5.95 5.93 5.94
5.94 5.94 5.94
5.94 5.96 5.95
5.97 5.98 5.975
6.02 5.95 5.985
5.99 5.98 5.985
6.02 5.97 5.995
6.00 6.10 6.05
6.093 6.137 6.115
6.11 6.14 6.125
6.15 6.19 6.17
Average of 54 sets = 5.828 ppm
Standard deviation of 54 sets = 0.149 ppmRelative standard deviation = 2.6 %95% Confidence interval for average: = +/- 0.041 ppm
Gold (ppm)
Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 5 of 6
Participating Laboratories
Australia ALS Minerals, Burnie
ALS Minerals, Kalgoorlie
ALS Minerals, Orange
ALS Minerals, Perth
ALS Minerals, Townsville
Bureau Veritas Amdel, Adelaide
Bureau Veritas Amdel, Kalgoorlie
Intertek Genalysis Laboratory Services, Perth
Burkina Faso ALS Minerals, Burkina Faso
SEMAFO Burkina Faso S.A.
Canada Acme Analytical Laboratories, Vancouver
ALS Minerals, Val-d’Or
ALS Minerals, Vancouver
Bourlamaque, Quebec
Loring Laboratories (Alberta) Ltd, Calgary
SGS Minerals Services, Lakefield, Ontario
SGS Minerals Services, Vancouver
Techni-Lab S.G.B. Abitibi Inc/Actlabs, Val d’Or
Techni-Lab S.G.B. Abitibi Inc/Actlabs, Ste-Germaine-Boule
TSL Laboratories Inc, Saskatoon
Chile Acme Analytical Laboratories, Santiago
Côte d’Ivoire Bureau Veritas Mineral Laboratories, Abidjan
Ghana ALS Minerals, Kumasi
SGS Performance Lab, Obuasi AngloGold
Ireland ALS Minerals, Loughrea
Kyrgyz Republic Stewart Assay and Environmental Laboratories LLC, Kara-Balta
Laos ALS Geochemistry, Vientiane
Mali ALS Minerals, Bamako
Mongolia ALS Minerals, Ulaanbaatar
Namibia Bureau Veritas- Mineral Laboratories, Swakopmund
New Zealand SGS New Zealand Ltd, Otago
SGS New Zealand Ltd, Reefton
SGS New Zealand Ltd, Waihi
Peru ALS Minerals, Lima
Inspectorate Services Perú S.A.C., Callao
Minera Yanacocha SRL – Newmont, Lima
Romania ALS Minerals, Rosia Montana
Russia Irgiredmet Analytical Centre, Irkutsk
South Africa AB Analytical Laboratory Services, Boksburg
Acme, Inspectorate M & M, Rustenburg
ALS Minerals, Edenvale
SibanyeGold, Driefontein Operations
Performance Laboratories, Barberton
Performance Laboratories, Randfontein
Performance Laboratories, Allanridge
Turkey Acme Analitik Laboratuar Hizmetleri Ltd, Sirketi
ALS Minerals, Izmir
USA ALS Minerals, Reno
Barrick Goldstrike – Met Services, Nevada
Inspectorate, Sparks
Newmont Mining Corporation, Carlin
Newmont Mining Corporation, Lone Tree
Newmont Mining Corporation, Twin Creeks
Zimbabwe Performance Laboratories, Ruwa
Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 6 of 6
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis, and analyse for total gold by normal
procedure. Homogeneity testing has shown that consistent results are obtainable for gold
when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This
confidence interval reflects our uncertainty in estimating the true value for the gold
content of the reference material. The interval is chosen such that, if the same procedure as
used here to estimate the declared value were used again and again, then 95% of the trials
would give intervals that contained the true value. It is a reflection of how precise the trial
has been in estimating the declared value. It does not reflect the variability any particular
laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how
different an individual test result should be from the declared value. Some mistakenly use
this interval, or the standard deviation from the consensus test, to set limits for control
charts on their own routine test results using the reference material. Such use inevitably
leads to many apparent out-of-control points, leading to doubts about the laboratory’s
testing, or of the reference material itself.
A much better way of determining the laboratory performance when analysing the
reference material is to accumulate a history of the test results obtained, and plot them on a
control chart. The appropriate centre line and control limits for this chart should be based
on the average level and variability exhibited in the laboratory’s own data. This chart will
provide a clear picture of the long-term stability or otherwise of the laboratory testing
process, providing good clues as to the causes of any problems. To help our customers do
this, we can provide a free Excel template that will produce sensible graphs, with
intelligently chosen limits, from the customer’s own data.
Legal Notice:
This certificate and the reference material described in it have been prepared with due care
and attention. However ROCKLABS Ltd, Scott Technology Ltd and Tim Ball Ltd accept
no liability for any decisions or actions taken following the use of the reference material.
References:
For further information on the preparation and validation of this reference material please
contact Brett Coombridge.
Certifying Officer Independent Statistician
Brett Coombridge (M.Phil. Chemistry) Tim Ball BSc (Hons)
Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 1 of 6.
Certificate of Analysis
Reference Material OxL51
Recommended Gold Concentration: 5.850 µg/g
95% Confidence Interval: +/- 0.051 µg/g
The above values apply only to product in jars or sachets which have an identification number within the following range: 113 965 – 115 300.
Prepared and Certified By: Malcolm Smith BSc, FNZIC Malcolm Smith Reference Materials Ltd 40 Oakford Park Crescent, Greenhithe, Auckland 1311 NEW ZEALAND
Email: [email protected]
Telephone: +64 9 444 3534
Fax: +64 9 444 7739
Date of Certification: 13 March 2006
Certificate Status: Original
Available Packaging: This reference material has been packed in wide-mouthed jars that contain 2.5 kg of product. The contents of some jars may be subsequently repacked into sealed polyethylene sachets.
Origin of Reference Material: Feldspars with minor quantities of finely divided gold-containing minerals that have been screened to ensure there is no gold nugget effect.
Supplier of Reference Material: ROCKLABS Ltd P O Box 18 142 Auckland NEW ZEALAND
Email: [email protected] Website: www.rocklabs.com Telephone: +64 9 634 7696
Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 2 of 6.
Description: The component minerals have been well mixed and a homogeneity test carried out after the entire batch was packaged into wide-mouthed jars to ascertain that the gold is evenly distributed throughout the reference material. There is no soil component. The product contains crystalline quartz and therefore dust from it should not be inhaled.
The approximate chemical composition is:
(Uncertified Values) %
SiO2 67.26
Al2O3 19.11
Na2O 8.54
K2O 3.62
CaO 0.21
MgO 0.17
TiO2 0.03
MnO 0.00
P2O5 0.09
Fe2O3 0.53
L O I 0.34
Intended Use: This reference material is designed to be included with every batch of samples analysed and the results plotted for quality monitoring purposes.
Stability: The container (jar or sachet) and its contents should not be heated to temperatures higher than 50 °C. The reference material is stable, with weight changes of less than 0.5 % at extremes of naturally occurring temperature and humidity conditions.
Method of Preparation: Pulverized feldspar minerals were blended with finely pulverized and screened, gold-containing minerals. Once the powders were uniformly mixed the composite was placed into 1336 wide-mouthed jars, each bearing a unique number. 40 jars were randomly selected from the packaging run and material from these jars was used for both homogeneity and consensus testing.
Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 3 of 6.
Homogeneity Assessment:
An independent laboratory carried out all gold analyses by fire assay of 30 g portions, using a gravimetric finish with a balance capable of reading to one microgram. Steps were taken to minimize laboratory method variation in order to better detect any variation in the candidate reference material. Homogeneity Assessment After Packaging
The contents of five randomly selected jars were compacted by vibration (to simulate the effect of freighting) and five samples removed successively from top to bottom from each jar. In addition, five samples were removed from the last jar in the series. A sample was removed from the top of each of the 40 jars randomly selected from the 1336 jars in the batch. The results of analysis of the 70 samples (randomly ordered and then consecutively numbered before being sent to the laboratory) produced a coefficient of variation of 0.5 %.
Analytical Methodology:
Once homogeneity had been established, two sub-samples were submitted to a number of well-recognized laboratories in order to assign a gold value by consensus testing. The sub-samples were drawn from the 40 randomly selected jars and each laboratory received samples from two different jars. Indicative concentration ranges were given. All laboratories used fire assay for the gold analysis.
Calculation of Certified Value:
Results for gold were returned from 29 laboratories. Statistical analysis to identify outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994. Assessment of each laboratory’s performance was carried out on the basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1. Details of the criteria used in these examinations are available on request. As a result of these statistical analyses, four sets of results were excluded for the purpose of assigning a gold concentration value to this reference material. A recommended value was thus calculated from the average of the remaining n = 25 sets of replicate results. The 95 % confidence interval was estimated using the formula:-
X ± ts/√n (where X is the estimated average, s is the estimated standard deviation of the laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-1 degrees of freedom). The recommended value is provided at the beginning of the certificate in µg/g (ppm) units. A summary of the results used to calculate the recommended value is listed on page 4 and the names of the laboratories that submitted results are listed on page 5.
Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 4 of 6.
Summary of Results Used to Calculate Gold Value (not related to order of laboratories listed on page 5)
Statistical analysis of both homogeneity and consensus test results has been carried out by independent statistician, Tim Ball.
Gold (ppm)
Sample 1 Sample 2 Average
5.562 5.685 5.6245.53 5.77 5.6505.69 5.63 5.660
5.700 5.665 5.6835.763 5.727 5.7455.78 5.80 5.790
5.830 5.773 5.8025.88 5.74 5.810
5.885 5.765 5.8255.78 5.87 5.8255.83 5.83 5.8295.83 5.88 5.8535.85 5.87 5.8585.89 5.83 5.860
5.865 5.860 5.8635.829 5.907 5.8685.81 5.96 5.8855.88 5.94 5.905
5.915 5.900 5.9085.94 5.88 5.910
5.945 5.895 5.9205.95 5.94 5.9456.02 6.01 6.0156.06 6.09 6.075
6.153 6.134 6.144
Average of 25 sets = 5.850 ppmStandard deviation of 25 sets = 0.123 ppm
Coefficient of variation = 2.1 %95% Confidence interval for average = 0.051 ppm
Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 5 of 6.
Participating Laboratories
Australia ALS Chemex, Perth Amdel Ltd, Adelaide Amdel Laboratories Ltd, Perth
Amdel Ltd, Kalgoorlie Genalysis Laboratory Services Pty Ltd, Perth SGS Australia Pty Ltd, Perth SGS Australia Pty Ltd, Townsville Standard and Reference Laboratories, Perth Ultra Trace Analytical Laboratories, Perth
Canada Accurassay Laboratories, Ontario Acme Analytical Laboratories Ltd, British Columbia ALS Chemex, British Columbia ALS Chemex, Quebec Assayers Canada, British Columbia Bourlamaque Assay Laboratories Ltd, Quebec International Plasma Labs Ltd, British Columbia Loring Laboratories Ltd, Alberta TSL Laboratories Inc, Saskatchewan
Kyrgyzstan Alex Stewart Assay and Environmental Laboratories Ltd
New Zealand Amdel Ltd, Otago SGS New Zealand Ltd, Waihi
Russia Irgiredmet, Irkutsk Norilsk Nickel, Trans-Polar Division Russian Academy of Science, Karelia
South Africa MINTEK, Analytical Science Division SGS Lakefield Research Africa (Pty) Ltd
United States of America ALS Chemex, Nevada Barrick Goldstrike Mines Inc, Nevada Newmont Mining Corporation, Nevada
Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 6 of 6.
Instructions and Recommendations for Use:
Weigh out quantity usually used for analysis and analyze for total gold by normal procedure. Homogeneity testing has shown that consistent results are obtainable for gold when 30g portions are taken for analysis.
We quote a 95% confidence interval for our estimate of the declared value. This confidence interval reflects our uncertainty in estimating the true value for the gold content of the reference material. The interval is chosen such that, if the same procedure as used here to estimate the declared value were used again and again, then 95% of the trials would give intervals that contained the true value. It is a reflection of how precise the trial has been in estimating the declared value. It does not reflect the variability any particular laboratory will experience in its own repetitive testing.
Some users in the past have misinterpreted this confidence interval as a guide as to how different an individual test result should be from the declared value. Some mistakenly use this interval to set limits for control charts on their own routine test results using the reference material. Such use inevitably leads to many apparent out-of-control points, leading to doubts about the laboratory’s testing, or of the reference material itself. A much better way of determining the laboratory performance for testing the reference material is to accumulate a history of the test results obtained, and plot them on a control chart. The appropriate centre line and control limits for this chart should be based on the average level and variability exhibited in the laboratory’s own data. This chart will provide a clear picture of the long-term stability or otherwise of the laboratory testing process, providing good clues as to the causes of any problems. To help our customers do this more simply for themselves, we can provide a free Excel template that will produce sensible graphs, with intelligently chosen limits, from the customer’s own data.
Legal Notice:
This certificate and the reference material described in it have been prepared with due care and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the reference material.
References:
For further information on the preparation and validation of this reference material please contact Malcolm Smith.
Certifying Officer Independent Statistician
M G Smith BSc, FNZIC Tim Ball BSc (Hons)