Use of the RHA information language for systematisation of alkaline and some other rock

types on their modal mineral composition

Krasnova N.I.* & Burnaeva M.Yu.**

*Saint-Petersburg State University, Saint Petersburg, Russia ** FGUP “BNIIOkeangeologia”, Saint Petersburg, Russia

2012

Using the traditional approaches to a problem of classification of many

magmatic rock types of we had shown, that, e.g., the alkaline rich rocks,

far not always allow distinguishing and identifying them unequivocally.

By displaying of chemical composition of different groups of rocks at

TAS diagrams their fields very often strongly overlap each other.

TAS

35 40 45 50 55 60 65 70 75 800

2

4

6

8

10

12

14

16

SiO2 (wt%)

NA2O+K2O (wt%)

Phono-tephrite

AndesiteAndesite-basaltPicro-

basalt

Basalt

Tephrite,Basanite

Trachy-basalt

Basalt- trachy- andesite

Trachy-andesite

Trachyte,Trachydacite

Rhyolite

Phono-tephrite

Foidite Tephri-phonolite

Phonolite

2203-synnyrites All

1000-minette-new

1047-lamproites_all

1524-t2-kimb-diamond_Milashev

2025-t1_alkaline rocks_Khibina

2201-t38-43_dikes Kola

1168-t1-6_gabbro_Talnakh

Composition of some K-bearing rocks at TAS diagram.

Composition of some K-bearing rocks at diagram K / Al at.%

0 1 2 3 4 5 6 7 8 9 10

0

1

2

3

4

5

6

7

8

9

10

Al at%

K at%

2203-synnyrites All

1000-minette-new

1047-lamproites_all

1524-t2-kimb-diamond_Milashev

2025-t1_alkaline rocks_Khibina

2201-t38-43_dikes Kola

1168-t1-6_gabbro_Talnakh

synnyrites

minettes

kimberlites

lamproites

Kola dikesgabbro

Khibinaalkaline rocks

K > Al

Al > K

The chemical composition of these rock groups some better shows this diagram.

K a

t.%

Use of the consecutive scheme for classification of magmatic rocks, according M. Le Bas and A. Streckaisen (1991) and recommendations of IUGS and the Petrographic Code approved by Russian IPC, also causes some questions. So, not clearly why some borders between groups of compositions are appointed on some "round" figures (10, 50, 75, etc. %%) concentrations of any components (oxides, minerals in modal, and sometimes normative volume %, or their incorporated groups – e.g., foids – F, or mafic minerals – M). As other classification principle distinctions of rocks by their composition and composition, agpaite factor are used also, etc. in existing classifications the general and uniform system of the description, ordering, and also an opportunity of comparison with known objects of new compositions have not been incorporated.

In existing classifications the general and uniform system of the description, ordering, and also an opportunity of comparison with known objects of new compositions have not been incorporated. Use of information language-method RHA developed more 40 years ago (Petrov, 1971) has allowed to begin drawing up on its basis of catalogues of a chemical composition of rocks (see file CollStart_En-2012 with data for more than 6410 inputs) and mineral composition in volumetric % (Vol. %) according to calculation of normative contents of minerals (601 analyses of lamprophyres + 475 of alkaline rocks) and now modal compositions (860 analyses). This offered method allows ordering unequivocally all compositions without any exception. The address for our data: http://geology.spbu.ru/department/scientific/rha-language-method

9-7-t39_Mag-Ap-Fo-Cal ore_Vuoriyarvi - CB Cal - doubtful diagnostic new diagnostic

1 2 3 4 5 6 En An DescriptionSerp Hbld Augt= Magt 0.730 0.085 8-960-t21_komatyte_Kenozero-Sumozero,KareliaAnlc Augt Oliv= Labr Magt Apat 0.785 0.066 185-960-t21_analcimite_Mt.Djebel-Zuaniv,AlgeriaAnlc Augt Oliv Labr Ortc 0.769 0.071 186-960-t21_analcimite_Spring Moung,AustraliaNtrl Aegn Ortc Arfv Biot Ilmt 0.794 0.082 1-2218-p74_syenite alkaline_Pukh-Ozero,KolaDolm Apat Magt Calc Phlg 0.420 0.161 7-1014-t6.1_CB Dol,721/78_KovdorDolm Magt Apat Phlg Calc 0.329 0.216 8-1014-t6.1_CB Dol,722/78_KovdorCalc Dolm Apat Magt Phlg 0.556 0.119 6-1014-t6.1_CB Cal,724/78_KovdorCalc Dolm Apat Magt Phlg 0.528 0.132 5-1014-t6.1_CB Cal,723/66_KovdorCalc Phlg= Oliv Magt Apat 0.947 0.018 10-7-t39_Fo-Phl-Cal ore_Vuoriyarvi,Kola CB CalCalc Oliv Apat Magt Phlt 0.930 0.028 9-7-t39_Mag-Ap-Fo-Cal ore_Vuoriyarvi,Kola CB CalCalc Aegn Apat Biot Albt Titn 0.602 0.151 1-7-t19_CB Aeg_OzernayaVaraka,KolaCalc Aegn Apat Andr Neph Magt 0.785 0.072 3-7-t19_CB Adr-Aeg-Cal_OzernayaVaraka,KolaCalc Trem Phlg Apat Pyrr 0.519 0.259 2-7-t41_CB Trm-Cal_Vuoriyarvi,KolaCalc Apat Phlg Oliv Pyrr Trem 0.426 0.155 1-7-t41_CB Cal_Vuoriyarvi,KolaCalc Apat Oliv Magt Phlg 0.436 0.161 3-1014-t6.1_CB Cal,514/III-78_KovdorCalc Apat Dips Magt Oliv 0.506 0.130 4-1014-t6.1_CB Cal,583/66_KovdorCalc Apat Magt Oliv 0.353 0.188 1-1014-t6.1_CB Cal,509/78_KovdorCalc Magt Oliv= Apat 0.238 0.243 2-1014-t6.1_CB Cal,508/78_KovdorCalc Magt Trem Phlg 0.790 0.072 5-7-t39_Trm-Mag-Cal ore_Vuoriyarvi,KolaCanc= Ortc Neph Arfv Sdlt Aegn 0.904 0.038 239-960-t21_naujaite_Ningurt,Lovozero,KolaCacn Hbld= Albt Aegn Ortc Titn 0.900 0.036 4-7-t14_tinguaite Arf_LesnayaVaraka,KolaSdlt Aegn Neph Biot Magt Canc 0.576 0.248 218-960-t21_tawite_Lovozero,KolaSdlt Aegn Ortc Canc Magt 0.416 0.244 219-960-t21_tawite_Lovozero,KolaPhlg Oliv Calc Mag Apat Pyrr 0.891 0.033 11-7-t39_Cal-Fo-Phl ore_Vuoriyarvi,KolaPhlg Oliv Magt= Apat Calc 0.870 0.035 1-1014-t5.2_forsteritite Phl,II-F/74_Kovdor phlogopititeOliv Serp Phlg Magt Dips Trem 0.373 0.193 2-1014-t3.1_olivinite,8741_KovdorOliv Serp Dips Magt Biot Hbld 0.727 0.073 4-1508-t23_olivinite Pyx,av.2_Kurginskyi,KolaOliv Serp Chrt Apat 0.518 0.308 14-960-t21_dunite_Voikar-Syn'insky,Polar UralOliv Serp Magt Biot Dips Hbld 0.606 0.158 2-1508-t23_olivinite,av.5_Kurginskyi,KolaOliv Calc Phlg Dips Magt Perv 0.687 0.084 1-7-t36_olivinite_Vuoriyarvi,KolaOliv Calc= Magt Apat Phlt Pyrr 0.960 0.015 6-7-t39_Ap-Mag-Cal-Fo ore_Vuoriyarvi,KolaOliv Phlg= Serp Magt Calc Dips 0.390 0.189 1-1014-t3.1_olivinite,8738_KovdorOliv Phlg= Calc Apat Trem Magt 0.470 0.139 7-1014-t4.1_forsteritite,8737_KovdorOliv Phlg Apat Dips Magt Calc 0.726 0.082 8-1014-t4.1_forsteritite,8725_KovdorOliv Phlg Apat= Magt Calc 0.907 0.026 3-1014-t5.2_forsteritite Phl,I-F/74_KovdorOliv Phlg Apat Magt Calc 0.794 0.074 2-1014-t5.2_forsteritite Phl,IV-F/74_Kovdor

1 Serpentine-ChrysotileSerp5 Analcime Anlc6 Natrolite Ntrl12 Dolomite Dolm13 Calcite Calc16 Cancrinite Canc17 Sodalite Sdlt22 Phlogopite Phlg23 Tetra-ferriphlogopiteTphl25 Olivine Oliv27 Corundum Corn34 Quartz Qutz35 Muscovite Musc37 Nepheline Neph39 Biotite Biot43 Albite Albt44 Aegirine Aegn47 Tremolite Trem50 Diopside Dips51 Augite Augt52 Hyperstene Hypr54 Oligoclase Olig55 Andesine Ands57 Leucite Lect58 Orthoclase Ortc59 Labradorite Labr61 Anorthite Anrt62 Wollastonite Woll64 Melilite Mell65 Titanite Titn66 Andradite Andr67 Hedenbergite Hedn71 Arfvedsonite Arfv72 Almandine Almn73 Hornblende Hbld74 Epidot Epid75 Zircon Zirc81 Apatite Apat82 Perovskite Perv84 Ilmenite Ilmt85 Chromite Chrt88 Magnetit Magt

Fragment of RHA Table of Modal Mineral rock composition (total an. = 865) Alphabet for RHA Table

33.4 25.2 25.1 11.8 4.3 Vol.%

93.0 3.0 2.0 2.0 Vol.%

Fragment of RHA Table of Modal Mineral ultrabasic rock composition

Fragment of RHA Table of Modal Mineral acidic rock composition

Microcline

Microcline

Real comp.

Except of rank formula (ranks 1-4 + 5-6), the RHA description includes the calculation of complexity (H or En), which shows the degree of monominerality composition, and purity (A or An) of rock’s analysis.

1 2 3 4 5 6 En An DescriptionOliv= Augt Hypr= Labr Ilmt 0.895 0.034 6-2218-t5_peridotite_Monche-Tundra,KolaOliv Augt Labr Biot Magt Hypr 0.835 0.044 104-960-t21_picrobasalt-picrodolerite_Norilsk reg.Oliv Augt= Labr Hbld Biot Magt 0.631 0.103 6-960-t21_picrite_r.Karatugay,KazakhstanOliv Augt Magt Ortc Ilmn Apat 0.858 0.054 2-1508-t8_peridotite,av.5_Gremyakha-VyrmesOliv Augt Magt Apat Ilmn Labr 0.779 0.085 2-1508-t6_peridotite,av.6_Gremyakha-VyrmesOliv Augt Magt Apat 0.215 0.354 11-960-t21_olivinite_Konzhakovskiy Kamen,UralOliv Augt Magt Chrt 0.561 0.278 23-960-t21_wehrlite_Kytlym,Ural,RussiaOliv Hypr Augt= Serp Labr Chrt 0.839 0.042 20-960-t21_lherzolite_Kraka,S.Ural,RussiaOliv= Hypr Augt Chrt 0.743 0.096 21-960-t21_lherzolite_volc.Tepl-Danun,S.SyriaOliv Hypr Augt Chrt Hbld 0.520 0.156 17-960-t21_harzburgite_Voikar-Syn'insky,N.UralOliv Hypr Labr Chrt Augt 0.604 0.165 18-960-t21_harzburgite_Monchegorsk pluton

1 2 3 4 5 6 En An DescriptionQutz= Albt= Ortc Biot Zirc 0.850 0.068 386-960-t21_ granite Mic-Ab_Polar UralQutz= Albt= Ortc Biot Zirc 0.817 0.114 395-960-t21_leucogranite Mic-Ab_ChukotkaQutz= Ortc= Albt Biot Magt Zirc 0.842 0.077 389-960-t21_granite subalkaline_Grodekovsky mass.Qutz= Ortc Albt Biot Epid Magt 0.629 0.167 384-960-t21_granite alkaline_Yisky,Sikhote-AlinQutz Ortc Albt Aegn 0.870 0.047 425-960-t21_leucogranite alkaline Mic-Ab_KolaQutz Ortc Albt Aegn Arfv 0.851 0.045 3-2218-t4_granite alkaline_I_Kuchuaiv,KolaAlbt Qutz= Ortc Augt Magt Hypr 0.802 0.078 420-960-t21_granite alkaline_Tarbagatai,KazakhstanAlbt Qutz= Ortc Magt 0.927 0.022 426-960-t21_leucogranite alk._Tarbagatai,KazakhstanAlbt= Ortc Qutz Biot Musc 0.943 0.017 350-960-t21_granite subalkaline_LyuchikhezskyiAlbt= Ortc Qutz Biot Musc 0.884 0.043 354-960-t21_granite_Vostok-2,Primorski reg.Albt Ortc= Qutz Biot Perv Hbld 0.843 0.060 351-960-t21_granite subalkaline_Nizyavr lake,KolaOlig Qutz Biot Ortc Epid Apat 0.790 0.059 2-2218-t3_granite, grey_110_Ponoy reg.Olig Qutz Biot Ortc Musc Chlr 0.741 0.090 348-960-t21_plagiogranite_Kalanti reg.,FinlandOrtc Qutz= Albt Musc Biot 0.808 0.110 357-960-t21_leucogranite_Baley,Central KazakhstanOrtc Qutz Albt Biot Zirc 0.937 0.019 387-960-t21_granite Mic-Ab_Pevek,ChukotkaOrtc Qutz Albt Biot Magt 0.848 0.056 353-960-t21_granite_Kim-Boy cap,Viet-NamOrtc Qutz= Albt Biot 0.799 0.145 1-2218-p36_aplite_Umba reg.

1 2 3 4 5 6 En An DescriptionAugt Labr Magt Oliv Apat Biot 0.948 0.022 6-2217-t11_gabbro ore, 901-1_Yelet'-Ozero,KolaAugt Labr Magt Oliv Apat Biot 0.925 0.028 5-2217-t11_gabbro ore, 900_Yelet'-Ozero,KolaAugt Labr Magt Oliv Biot Apat 0.865 0.055 14-2217-t11_gabbro ore Ort, 1568_Yelet'-OzeroAugt Labr Magt Oliv Hbld Trem 0.793 0.066 3-2217-t10_gabbro ore, 674_Yelet'-Ozero,KolaAugt Magt Oliv Labr Apat Hbld 0.919 0.028 28-2217-t10_gabbro ore, 809/1_Yelet'-Ozero,KolaAugt Magt= Oliv Labr Ilmn Apat 0.855 0.055 18-1508-t2_gabbro ore,av.6_Yelet'-Ozero,NyatovaraHypr= Oliv Biot= Magt Chrt 0.740 0.089 36-960-t21_F picrite_Maimecha-Kotui,E.SiberiaHypr Oliv Labr Magt 0.327 0.311 143-960-t21_orthopyroxenite Ol_Monchegorsk intr.Hypr Oliv Magt Augt Labr 0.746 0.079 144-960-t21_orthopyroxenite Ol_MonchetundraHypr Dips Oliv= Hbld 0.430 0.467 2-2222-t5_hypobasite vein_563_Tundra wolf,KolaHypr Dips Labr Oliv 0.609 0.257 4-2222-t3_pyroxenite Pl_372_Tundra wolf,KolaHypr Augt Labr Magt 0.296 0.239 140-960-t21_orthopyroxenite_Monchegorsk plutonHypr Augt Magt= Hbld 0.340 0.424 147-960-t21_websterite_Voikar-Synninsky,N.UralHypr Labr Dips Oliv 0.868 0.034 6-2222-t3_gabbro-pyroxenite Ol_374_Tundra wolfOlig Qutz Biot Ortc Hbld Magt 0.753 0.067 282-960-t21_diorite subalkaline Qtz_Primorski reg.Olig Ortc Qutz= Augt Hbld Magt 0.774 0.067 281-960-t21_diorite subalkaline Qtz_Santorin,GreeceOrtc Albt Qutz Arfv Aegn Magt 0.860 0.045 414-960-t21_syenite Qtz alkal._Gremyakha-VyrmesOrtc Albt Qutz Arfv Aegn Magt 0.579 0.113 411-960-t21_nordmarkite_Gremyakha-Vyrmes,KolaLabr Oliv= Augt Trem Biot Magt 0.745 0.070 6-2217-t6_gabbro Ol, 647_Yelet'-Ozero,Kola,KolaLabr= Oliv Augt Trem Magt Serp 0.684 0.123 7-2217-t6_gabbro Ol, 632_Yelet'-Ozero,Kola,KolaLabr Oliv Augt Hypr 0.908 0.021 177-960-t21_gabbronorite Ol_Chuna Tundra ridgeLabr Oliv Augt= Hypr Magt 0.698 0.104 180-960-t21_troctolite_Tchajatchy Isl.,N.KareliaLabr Qutz Trem= Ortc Biot Zirc 0.812 0.056 341-960-t21_granodiorite_r.Strelna,KolaLabr Qutz= Ortc Biot Serp Musc 0.876 0.047 342-960-t21_granodiorite_Svanetia,Caucasus,GeorgiaLabr Qutz Ortc= Biot Magt 0.774 0.058 288-960-t21_diorite Qtz_Myao-Chansky,r.AmurLabr Qutz Hbld Biot Ortc Epid 0.761 0.071 254-960-t21_diorite Qtz_Mutuhe bay,Primorskiy reg.Labr= Augt Oliv Magt Apat Ilmn 0.902 0.037 16-1508-t2_gabbro ore,av.6_Yelet'-Ozero,NyatovaraLabr Augt Oliv= Magt Apat Biot 0.864 0.041 7-2217-t11_gabbro ore, 901-2_Yelet'-Ozero,KolaLabr= Augt Oliv Magt 0.839 0.047 107-960-t21_basalt-dolerite Ol_S.Damask,SyriaLabr Augt Oliv Magt Biot Trem 0.801 0.084 9-2217-t6_gabbro Ol, 628_Yelet'-Ozero,KolaMagt Labr Trem Augt Spnl Hbld 0.888 0.038 1-2217-t10_gabbro ore, 501_Yelet'-Ozero,KolaMagt Labr Trem= Augt Spnl Hbld 0.744 0.083 7-2217-t10_gabbro ore, 700a_Yelet'-Ozero,KolaMagt= Labr Augt Oliv Spnl Hbld 0.789 0.077 18-2217-t10_gabbro ore, 805 av_Yelet'-Ozero,KolaMagt Labr Augt Oliv Hbld Spnl 0.732 0.099 16-2217-t10_gabbro ore, 805/1_Yelet'-Ozero,KolaMagt Labr Augt Trem Spnl Oliv 0.791 0.070 9-2217-t10_gabbro ore, 802/1_Yelet'-Ozero,KolaMagt Labr Augt Hbld Oliv Spnl 0.864 0.050 22-2217-t10_gabbro ore, 807/1_Yelet'-Ozero,KolaMagt Labr Augt Ilmn Oliv Trem 0.881 0.050 12-1508-t2_gabbro ore,av.8_Yelet'-Ozero,Kola

Fragment of RHA Table of Modal Mineral gabbro series rock composition

Fragment of RHA Table of Modal Mineral urtite-ijolite-melteigite series rock composition

Modal mineral composition of urtite-melteigite rock series at Neph-Aegn diagram

10 20 30 40 50 60 70 80 90

0

10

20

30

40

50

60

70

80

Neph

Aegn

2219-etc_ijolites All-2

2219-etc_urtites All-2

2219-etc_jacupirangites All-2

2219-etc_melteigites-All-2

Neph-68.9, Aegn-20.8, Titn-4,Vol.% ijolite

Neph-69.6, Aegn-21.2, Titn-5.6 urtite

Neph Aegn Titn Apat

Neph Aegn Titn Apat

IUGS: Urtite has more than 70% of Neph; ijolite has 30-70% of Neph. For points shown by arrows will be better

more common name urtite-ijolite. The names for rock compositions, which overlap each other, should be revised

more careful.

Aeg

n V

o l.%

Fragment of RHA Table of Modal Mineral melilite-bearing rock composition

1 2 3 4 5 6 En An DescriptionOliv= Mell Mtcl= Dips Trem Perv 0.945 0.019 26-1010-t5_kugdite Pyx_Guli,Maymecha-KotuiOliv Mell Magt= Phlg Anlc Neph 0.780 0.071 39-960-t21_picrite alkaline_N-E Siberia plateOliv Mell= Magt= Perv Mtcl Serp 0.979 0.009 2-7-t20_olivinite Mel_Afrikanda,KolaNeph Mell Oliv Trem Perv Dips 0.785 0.068 21-1010-t5_okaite Ol_Kara-Meni,Maymecha-KotuiNeph Mell Dips Perv Phlg 0.833 0.056 37-1014-t3.3_turjaite Pyx_KovdorNeph= Mell Dips Magt 0.768 0.090 34-1014-t3.3_turjaite Pyx_KovdorDips Mell= Neph Oliv Phlg Trem 0.903 0.040 15-1010-t5_turjaite Ol_Nemakit,Maymecha-KotuiDips Mell Neph= Trem Mtcl Oliv 0.922 0.030 11-1010-t5_turjaite-57/7_Changit,Maymecha-KotuiDips Mell Magt Phlg Neph 0.802 0.063 21-1014-t3.3_uncompagrite_KovdorDips Mell Magt Phlg Oliv Mont 0.751 0.093 20-1014-t3.3_uncompagrite_KovdorMell Phlg Neph= Perv Magt 0.832 0.047 27-1014-t3.3_turjaite Phl_KovdorMell Phlg Neph Magt Dips Perv 0.823 0.043 26-1014-t3.3_turjaite Phl_KovdorMell Phlg Neph Magt 0.349 0.290 6-1014-t3.3_melilitolite_KovdorMell Phlg= Magt Perv 0.335 0.193 4-1014-t3.3_melilitolite_KovdorMell Mont Dips= Magt Oliv Trem 0.624 0.106 13-1014-t3.3_Mont-Mel_KovdorMell Mont= Dips Magt Oliv Perv 0.617 0.097 12-1014-t3.3_Mont-Mel_KovdorMell Oliv Phlg= Trem Neph 0.900 0.026 24-1010-t5_kugdite-608/30_Guli,Maymecha-KotuiMell Oliv Mont= Dips Phlg Magt 0.714 0.077 16-1014-t3.3_kugdite_KovdorMell Oliv= Biot Neph Magt Apat 0.957 0.016 51-960-t21_melilitite Ol_Polzen,CzekhMell Oliv Trem Dips Phlg Mtcl 0.617 0.121 23-1010-t5_kugdite_Kugda,Maymecha-KotuiMell= Neph Hayn Calc Magt Biot 0.736 0.100 87-960-t21_okaite_Oka,Quebec,CanadaMell Neph Phlg Dips Magt 0.567 0.152 15-1014-t3.3_okaite_KovdorMell Neph Phlg Magt Perv Dips 0.412 0.203 14-1014-t3.3_okaite_KovdorMell Neph Trem Phlg Oliv Dips 0.782 0.069 20-1010-t5_okaite_E.Bykhyt,Maymecha-KotuiMell Neph Dips Phlg Trem Andr 0.727 0.086 18-1010-t5_okaite Pyx_Odikhincha,MaymechaMell Neph Dips Magt Phlg Perv 0.873 0.040 33-1014-t3.3_turjaite Pyx_KovdorMell Neph Andr Phlg Trem Perv 0.938 0.018 22-1010-t5_okaite-173-b_Nemakit,Maymecha-KotuiMell Neph Magt Phlg Oliv 0.715 0.119 86-960-t21_okaite_Kara-Meni,Maymecha-KotuiMell Trem Dips Phlg Perv Oliv 0.544 0.152 2-1010-t5_uncompahgrite_Kugda,Maymecha-KotuiMell Trem Dips Oliv Neph 0.562 0.115 5-1010-t5_uncompahgrite Ne_W.Bykhyt,MaymechaMell Dips Phlg Magt Perv 0.312 0.214 2-1014-t3.3_melilitolite_KovdorMell Dips Andr Phlg Qutz Trem 0.509 0.313 1-1010-t5_uncompahgrite-598_Odikhincha,MaymechaMell Dips Perv Magt 0.777 0.062 18-1014-t3.3_uncompagrite_KovdorMell Augt Andr Magt 0.511 0.284 81-960-t21_uncompagrite_Odikhincha,MaymechaMell Augt Magt Perv Biot Oliv 0.695 0.084 14-676-t3.4_uncompahgrite_Rangwa,S.AfricaMell Magt Phlg Perv Dips 0.357 0.238 7-1014-t3.3_melilitolite_KovdorMell Magt Dips Phlg 0.244 0.298 1-1014-t3.3_melilitolite_KovdorMell Magt Dips Oliv Mont Perv 0.579 0.113 11-1014-t3.3_melilitolite_Kovdor

50 25 10 10 5 Vol.%

88.9 4.6 4.5 2 Vol.%

So, on the presented material it is visible, that different on mineral

composition of group of rocks evidently differ using the RHA system, that,

naturally, reflects their visual diagnostics. Difficulties arise only at incorrect,

or uncertain diagnostics of rockforming minerals. Thus, for instance, often

authors specify only presence in rock of plagioclase, without definition of its

number, and also pyroxene or amphibole, not explaining to which group it is

necessary to its attribute. Specification of these data will demand attraction

of different experts – petrographers and mineralogists.

Comparison of RHA Tables of Modal and Normative Mineral rock composition, calculated using Norm-4

1. The first (dominating) minerals are mostly similar by calculation both of modal and normative mineral composition for different rock types. Sometimes the minerals in normative composition are rearranged as compared with modal rank formula.

2. Some virtual components, as leucite – Lect, K2SiO3, Na2CO3, corundum, larnite etc., are received sometimes at norms calculation.

3. The best conformity of modal and normative mineral composition is observed for gabbroid rock series, but it is senseless to calculate the normative composition of such rocks as dolomite-bearing carbonatites or phoscorites, melilite-bearing and some other rock types.

After critical revision of such full collections RHAmin data for different groups of rocks

from various regions of the world, it will be possible to work out for them the rational

nomenclature. Both tables of RHA-data, and the various plots constructed on their

basis, help to diagnose correctly rocks on the mineral composition determined in

volumetric %, to reveal erroneous diagnostics of some of rocks. Creation of the

representative RHA-catalogue of such full data for all rocks will provide an opportunity

of their unequivocal identification on the real mineral composition, opened for addition

new, before unknown types. In the future such classifications on method RHA can

become a perspective task for different groups of geologists of all world.

Thank you for attention!Thank you for attention!

Marina Burnaeva Natalia Krasnova