rock identification rock lab. identification of all three rock groups is based on texture and...
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Rock Identification Rock LabRock Identification Rock Lab
Identification of all three rock groupsis based on
TEXTURE and COMPOSITION
Identification of all three rock groupsis based on
TEXTURE and COMPOSITION
the appearance of thethe appearance of therockrock
the appearance of thethe appearance of therockrock
what the rock is madewhat the rock is madeout of – type of mineralsout of – type of mineralswhat the rock is madewhat the rock is made
out of – type of mineralsout of – type of minerals
Love it, Learn it, Live it , be one with it!Love it, Learn it, Live it , be one with it!
Igneous Rock ClassificationIgneous Rock Classification
Let’s form an igneous rock• Two major types of igneous rocks
Let’s form an igneous rock• Two major types of igneous rocks
Intrusive – magma solidifies below the Earth’s surface
•magma cools very slow•crystals form interlocking “mosaic” textures•very coarse-grained visible minerals•referred to as Plutonic rocks
Intrusive – magma solidifies below the Earth’s surface
•magma cools very slow•crystals form interlocking “mosaic” textures•very coarse-grained visible minerals•referred to as Plutonic rocks
Extrusive – magma solidifies above the Earth’s surface•magma cools very fast •minerals can not be seen with un-aided eye•very fine-grained texture (no visible minerals•referred to as Volcanic rocks
Extrusive – magma solidifies above the Earth’s surface•magma cools very fast •minerals can not be seen with un-aided eye•very fine-grained texture (no visible minerals•referred to as Volcanic rocks
Igneous Rock ClassificationIdentification of igneous rocks is based on two main characteristics
Texture – the appearance of the rock due to the rate of magma cooling
Composition – the type of minerals found in the rock (mineral composition)
Igneous Rock ClassificationIdentification of igneous rocks is based on two main characteristics
Texture – the appearance of the rock due to the rate of magma cooling
Composition – the type of minerals found in the rock (mineral composition)
Textures of Igneous Rocks
Intrusive rocks (Textural terms)
phaneritic texture – crystals are visible and form a mosaic of interlocking mineral aggregates (less than 1 cm)
Textures of Igneous Rocks
Intrusive rocks (Textural terms)
phaneritic texture – crystals are visible and form a mosaic of interlocking mineral aggregates (less than 1 cm)
Interlocking crystal grainsphaneritic texture
Interlocking crystal grainsphaneritic texture
Extrusive Igneous Rocks (textural terms)Extrusive Igneous Rocks (textural terms)
aphanitic texture – crystals are too small to seeaphanitic texture – crystals are too small to see
See, you really can not see any mineral crystalsSee, you really can not see any mineral crystals
• magma cooled extremely fast (quenched)
• not enough time for atoms to combine (amorphous solid)- lacks a crystalline structure
• magma cooled extremely fast (quenched)
• not enough time for atoms to combine (amorphous solid)- lacks a crystalline structure
glassy textureglassy texture
Igneous Rock Classification LabIgneous Rock Classification LabVesicular texture- sponge like appearance, texture contains
numerous cavities or holesVesicular texture- sponge like appearance, texture contains
numerous cavities or holes
Vesicles – gas bubbles cavities Vesicles – gas bubbles cavities
Pyroclastic texture – textures created by rapidly cooling lava that is “hurled” through the air picking up fragments
(tuffaceous texture)
Pyroclastic texture – textures created by rapidly cooling lava that is “hurled” through the air picking up fragments
(tuffaceous texture)
rock fragments – pieces of rock “incorporated” into the rock (tuffaceous)
rock fragments – pieces of rock “incorporated” into the rock (tuffaceous)
Igneous Rock Classification LabIgneous Rock Classification Lab
Igneous Rock Compositionmineral composition = mineral assemblages=
chemistryThe mineral is either ferromagnesian (dark
colored) or felsic (light colored
ferromagnesian (mafic) minerals rich in Fe, Mg – creates a dark colored
rocks
Igneous Rock Compositionmineral composition = mineral assemblages=
chemistryThe mineral is either ferromagnesian (dark
colored) or felsic (light colored
ferromagnesian (mafic) minerals rich in Fe, Mg – creates a dark colored
rocksPyroxene (Augite)Pyroxene (Augite)
Amphibole (hornblende)Amphibole (hornblende)Mica - BiotiteMica - Biotite
Igneous Rock Classification LabIgneous Rock Classification Lab
Igneous Rock Composition
Mineral composition = Mineral assemblages = ChemistryThe mineral is either ferromagnesian (dark colored) or felsic (light colored)
Felsic – mineral composition is light colored minerals
Igneous Rock Composition
Mineral composition = Mineral assemblages = ChemistryThe mineral is either ferromagnesian (dark colored) or felsic (light colored)
Felsic – mineral composition is light colored minerals
Ca-plagioclaseCa-plagioclase
K-feldspar (orthoclase)K-feldspar (orthoclase)
Mica- muscoviteMica- muscovite
QuartzQuartz
Ori
gin
Tex
ture
Intr
usi
ve
Ph
ane-
riti
c
Very coarse crystal grains, usually allgrains are approximately the same sizew/ respect to each other. Grains> one inch
A mosaic of coarse-grains that areeasily visible to the unaided eye – grainsgreater than 1 mm
Gra
nit
e
Gra
no
-d
iori
te
Dio
rite
Gab
bro
Per
ido
tite
GranitePegmatite
MaficPegmatite
Rh
yoli
te
Dac
ite
An
des
ite
Bas
alt
X
Ext
rusi
ve
Fine to very fine grains, usually to smallto be distinguished with the unaidedeye or even with a hand lensA
ph
an-
itic
Gla
ssy
Po
r-o
us
Fra
g-
men
tal
Obsidian
Pumice Scoria
RhyoliticTuff
BasalticTuff
80%
40%
20%
Glassy – non-crystalline, non-granularColor varies between black and brown
Highly vesicular, finely crystalline to glassyPumice (light), Scoria (dark)
Composed of fragments of all sizesProduced in volcanic environments, AshPartially re-fused or cemented
Ver
yC
oar
se
Rock Descriptions
Igneous Rock Classification Felsic Mafic
Sedimentary Rock Identification LabSedimentary Rock Identification Lab
Sandstone Arches
How is a sedimentary Rock formed???How is a sedimentary Rock formed???How is a sedimentary Rock formed???How is a sedimentary Rock formed???
Pre-existingPre-existingRockRock
Pre-existingPre-existingRockRock
ErosionErosionErosionErosion
Water, Wind, Water, Wind, IceIce
Water, Wind, Water, Wind, IceIce
Breaks downBreaks downPre-existing rockPre-existing rockBreaks downBreaks downPre-existing rockPre-existing rock
SedimentSedimentSedimentSediment
TransportedTransportedTransportedTransportedLakesLakesLakesLakes
RiversRiversRiversRivers
Depos
ited
Depos
ited
Depos
ited
Depos
ited
CompactedCompactedCementedCemented
CompactedCompactedCementedCemented
LithifiedLithifiedLithifiedLithified SedimentarySedimentaryRockRock
SedimentarySedimentaryRockRock
Why is the earth’s surface 75% sedimentary rocks?????????Why is the earth’s surface 75% sedimentary rocks?????????Why is the earth’s surface 75% sedimentary rocks?????????Why is the earth’s surface 75% sedimentary rocks?????????
Three major categories of Sedimentary Rocks
Clastic Sedimentary rocks
Chemical Sedimentary rocks
Bio-chemical (bio-clastic) Sedimentary rocks
Three major categories of Sedimentary Rocks
Clastic Sedimentary rocks
Chemical Sedimentary rocks
Bio-chemical (bio-clastic) Sedimentary rocks
Clastic (inorganic-detrital)rocks are composed of particles or grains. Rockname is dependent on grain size.
Decreasing grain size
Decreasing grain size2+ mm2+ mm
2 mm2 mm
1/16 mm1/16 mm
1/256 mm1/256 mm
Chemical Rocks – inorganic, non-clastic rocks that are commonly the result of evaporation and precipitation
Chemical rocks contain no fossils, or biological material but may react with HCl
Chemical Rocks – inorganic, non-clastic rocks that are commonly the result of evaporation and precipitation
Chemical rocks contain no fossils, or biological material but may react with HCl
The Great Salt Lake, Utahhalite (salt) crystals
The Great Salt Lake, Utahhalite (salt) crystals
Calcium Carbonate (CaCO3) chemical rocks (evaporation / precipitation processes)Calcium Carbonate (CaCO3) chemical rocks (evaporation / precipitation processes)
Chemically precipitated SiO2Chemically precipitated SiO2
Bio-chemical (bio-clastic, biogenic) rocks – result from animal and plant secretions. The term clasticindicates that these rocks contain fossils or parts of plantsshells, compacted plat material
Bio-chemical (bio-clastic, biogenic) rocks – result from animal and plant secretions. The term clasticindicates that these rocks contain fossils or parts of plantsshells, compacted plat material
Animal partsAnimal parts
Cemented shell fragmentsCemented shell fragments
Lithified plant materialLithified plant material
Classification ProcedureClassification Procedure
Step 1: Determine if the rock is clastic or non-clastic Step 1: Determine if the rock is clastic or non-clastic
Step 2: If the rock is clastic, determine the grain size and diagnostic properties. Make the ID.Step 2: If the rock is clastic, determine the grain size and diagnostic properties. Make the ID.
Step 3: If the rock is not clastic, determine if the rock is either chemical or bioclastic
chemical – will not contain particles such as grains and organic material. Test rock to observe fizzing (carbonates) Match diagnostic properties on chart for ID
bio-clastic- rock will be composed of particles that are organic- animal parts, plant secretions.
Test rock to observe fizzing (carbonate) Match diagnostic properties on chart for
ID
Step 3: If the rock is not clastic, determine if the rock is either chemical or bioclastic
chemical – will not contain particles such as grains and organic material. Test rock to observe fizzing (carbonates) Match diagnostic properties on chart for ID
bio-clastic- rock will be composed of particles that are organic- animal parts, plant secretions.
Test rock to observe fizzing (carbonate) Match diagnostic properties on chart for
ID
Metamorphic RocksMetamorphic Rocks
Meta (to change) morphic (form) = to change formMeta (to change) morphic (form) = to change form
Metamorphism– to change a rocks compositional and textural characteristics by subjecting the rock to various pressure/temperature relationships
Rocks undergo a solid-state-transformation
Metamorphism– to change a rocks compositional and textural characteristics by subjecting the rock to various pressure/temperature relationships
Rocks undergo a solid-state-transformation
The parent rock: represents the pre-existing rock metamorphism
Example: Shale (parent) Schist Limestone (parent) Marble
The parent rock: represents the pre-existing rock metamorphism
Example: Shale (parent) Schist Limestone (parent) Marble
Identification of Metamorphic RocksIdentification of Metamorphic Rocks
Identified by using the rocks Texture and CompositionIdentified by using the rocks Texture and Composition
Compositional characteristics – types of mineral presentcommon minerals: quartz, feldspar, muscovite
special minerals: talc, garnet, chlorite related to P/T relationships
Compositional characteristics – types of mineral presentcommon minerals: quartz, feldspar, muscovite
special minerals: talc, garnet, chlorite related to P/T relationships
Textural characteristics – minerals are oriented in various degrees of “parallelism”
platy sub-parallel parallel
Textural characteristics – minerals are oriented in various degrees of “parallelism”
platy sub-parallel parallel
Grain size distribution – fine-grain to coarse-grain reflects P/T relationshipsfine-grain coarse-grainLow P/T High P/T
Grain size distribution – fine-grain to coarse-grain reflects P/T relationshipsfine-grain coarse-grainLow P/T High P/T
FOLIATED
FOLIATED
Gneissic Schistose Slaty
Coarse-grainedHigh P/T
Fine-grainedLow P/T
Alternating lightand dark mineralbands
Alternating lightand dark mineralbands
Parallel to sub-parallelMineral alignmentParallel to sub-parallelMineral alignment
“compressed”layering - platy“compressed”layering - platy
Textural characteristicsTextural characteristics
Non-foliated texture – minerals are not visible and there orientation does not exist
Rock is composed of single type chemistry.
Non-foliated texture – minerals are not visible and there orientation does not exist
Rock is composed of single type chemistry.
NON-FOLIATEDNON-FOLIATED
Example: rocks composed of CaCO3
rocks composed of SiO2
Example: rocks composed of CaCO3
rocks composed of SiO2
Shows NO foliationComposed of ONE COMPOSITIONShows NO foliationComposed of ONE COMPOSITION
QuartzSiO2
QuartzSiO2
CalciteCaCO3
CalciteCaCO3
Plant MaterialC -carbonPlant MaterialC -carbon
How can oneTell the
Difference ?
How can oneTell the
Difference ?
“Fussed glass”Scratches glass
Hard H = 7
“Fussed glass”Scratches glass
Hard H = 7
“Sometimes xln”Fizzes in HCl
Soft H = 3
“Sometimes xln”Fizzes in HCl
Soft H = 3
Classification ProcedureClassification Procedure
Step 1:•Determine if the rock is foliated or non-foliated
•does the rock contain “parallelism” or grains•does the rock consist of a single chemistry with
no visible grains?
Step 1:•Determine if the rock is foliated or non-foliated
•does the rock contain “parallelism” or grains•does the rock consist of a single chemistry with
no visible grains?
Step 2:•If the rock is foliated
•examine the degree of “parallelism”•examine the grain-size distribution•refer to charts for ID
Step 2:•If the rock is foliated
•examine the degree of “parallelism”•examine the grain-size distribution•refer to charts for ID
Step 3:•If the rock is non-foliated
•determine the composition of the rock•determine the special characteristics•Refer to charts for ID
Step 3:•If the rock is non-foliated
•determine the composition of the rock•determine the special characteristics•Refer to charts for ID