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Calculation & Classification

Rock Analysis

Info

Clears all inputs and results and sets the ratio Fe₂O₃ to FeO to 0. This minimizes the processor load when re-entering! Alternatively, you can reload the page.

Enter the chemical analysis of your rock here:

SiO₂

TiO₂

Al₂O₃

Fe₂O₃

FeO

MnO

MgO

CaO

Na₂O

K₂O

P₂O₅

CO₂

SO₃

S

F

Cl

Sr

Ba

Ni

Cr

Zr

Total*

* Without trace elements




Options

Logging

Activate the logging of intermediate values in the console.

Normalization

Check this box if you want the calculated norm to be normalized to 100%.

Fe₂O₃ to FeO ratio (Correction)

Enter desired ratio of Fe₂O₃ to FeO. The default value is "0" (see info):

Fe3+/(Total Iron)

Info

Normally you calculate a norm using the analyzed Fe₂O₃ and FeO proportions. To do this just put a zero in the space to the right. Sometimes, if a rock has been chemically altered, metamorphosed, or if you don't have data for both Fe₂O₃ and FeO, you may want to use a standard ratio of these two components to calculate the norm. To choose a standard ratio, replace the zero in this space with a number from 0 to 1, corresponding to the desired molar ratio of Fe3+/(Total Iron). Common ratios used for rocks of the following compositions are: 0.1 for basalts and basaltic andesites, 0.15 for andesites, 0.2 for dacites, and 0.3 for rhyolites.


Total Fe as FeO

Desired Fe₂O₃

Desired FeO

Weight corr. factor

Norm calculation checks

About the norm checks

This box checks certain parts of the calculations to be sure they are consistent with a correct norm. The green OK message indicates that there is nothing grossly incorrect detected in this calculated norm. This does not necessarily mean that the norm is correct, and you should always check for data entry errors and the reasonableness of the norm itself.

The red warning message indicates that there is a problem with the norm. This may mean that your rock composition was typed in wrong, that the rock composition lies outside the composition space in which the norm is designed to work, or it may indicate a bug in the calculation program. First, check for data entry errors and control the composition of your rock. If this is not the problem, please contact Minetosh online.



For more information and explanations go the help page, please:

Help and infos


Normalized Analysis

SiO₂

TiO₂

Al₂O₃

Fe₂O₃

FeO

MnO

MgO

CaO

Na₂O

K₂O

P₂O₅

CO₂

SO₃

S

F

Cl

Sr

Ba

Ni

Cr

Zr

Total*

* This total includes the trace elements. The trace element values listed above have also been recalculated from ppm to the weight % of their respective oxides.

Result: CIPW Norm

Normative minerals

Weight % Norm

Volume % Norm

Quartz

Plagioclase

Orthoclase

Nepheline

Leucite

Kalsilite

Corundum

Diopside

Hypersthene

Wollastonite

Olivine

Larnite

Acmite

K₂SiO₃

Na₂SiO₃

Rutile

Ilmenite

Magnetite

Hematite

Apatite

Zircon

Perovskite

Chromite

Sphene

Pyrite

Halite

Fluorite

Anhydrite

Na₂SO₄

Calcite

Na₂CO₃

Total*

Info * Total weight % norm: Within rounding error (usually +/- 0.10) this total should be the same as the total for the Corrected Analysis. If not, either rounding error is excessive this time, your rock composition lies outside the composition space for which the CIPW norm was designed, or there is a bug in the program. — * Total volume % norm: The volume norm is always normalized to 100%, excluding rounding errors.

Fe³⁺/∑Fe
(rock)

Info The molar ratio of ferric (Fe³⁺) iron to total iron in the rock composition used for the norm (specifically the ratio in the Corrected Analysis). This ratio is a measure of the oxidation state of the rock. Expressed out of a maximum of 100%.

Mg/(Mg+∑Fe)
(rock)

Info The molar ratio of Mg to the total of Mg and Total Iron in the rock (specifically in the Corrected Analysis). This ratio is a measure of the differentiation of an igneous rock. This ratio is independent of the degree of oxidation of the iron in the rock. Expressed out of a maximum of 100%.

Mg/(Mg+Fe²⁺)
(rock)

Info The molar ratio of Mg to the total of Mg and Fe2+ in the rock (specifically in the Corrected Analysis). This ratio is a measure of the differentiation of an igneous rock. Expressed out of a maximum of 100%.

Mg/(Mg+Fe²⁺)
(Silcates)

Info The molar ratio of Mg to the total of Mg and Fe²⁺ in the normative silicates (olivine, diopside, and hypersthene). This ratio is a measure of the differentiation of an igneous rock. Expressed out of a maximum of 100%

Ca/(Ca+Na)
(Rock)

Info The molar ratio of Ca to the total of Ca and Na in the rock (specifically in the Corrected Analysis). This ratio is a measure of the differentiation of an igneous rock. Expressed out of a maximum of 100%.

Plagioclase
An content

Info The molar ratio of Ca/(Ca+Na) in the normative plagiolclase feldspar, expressed out of a maximum value of 100%. This ratio is one measure of the differentiation of an igneous rock.

Differentiation Index

Info Thornton-Tuttle differentiation index. This is the ratio of normative (quartz + albite + orthoclase + nepheline + leucite + kalsilite + sodium carbonate + sodium sulfate) to the weight total of the norm. This is a measure of the differentiation of an igneous rock. Note the two different values calculated for the weight and volume norms. Expressed out of a maximum of 100%.

Aluminum Saturation Index

Info Molar ratio Al₂O₃/((CaO–(3.33∙P2O5))+Na₂O+K₂O): Values < 1 are subaluminous, those > 1 are peraluminous. Generally, values 1.05–1.10 are sufficiently aluminous to have aluminous minerals such as muscovite, cordierite, garnet, or aluminosilicates. Rocks having values of 1.00–1.05 are sometimes referred to as metaluminous, having no Ca-rich minerals like hornblende and titanite, but also no aluminous minerals. Rocks having values < 1.0 typically have Ca-rich minerals like hornblende, augite, and titanite. Biotite is common in all.

Alkalinity Index

Info Molar ratio Al₂O₃/(Na₂O+K₂O): Values < 1 are peralkaline, values > 1 are subalkaline. Peralkaline rocks have more Na and K than can be accommodated in feldspars, and so stabilize Na- and K-rich minerals like riebeckite, aegirine, and astrophyllite. In contrast, subalkaline rocks tend to have hornblende, augite, and orthopyroxene. Biotite is common in both.

Calculated rock density [g/cm³]

Info The solid rock density calculated from the volume norm. Except for the exclusion of water in the norm (admittedly a substantial problem), this calculated value is probably quite accurate.

Calculated liquid density
[g/cm³]

Info Grams/cm³, calculated assuming a dry magma and the crudly estimated liquidus temperature given below. From McBirney, A.R., 1993, Igneous Petrology, Second Edition. Appendix B, in, Jones and Bartlett Publishers, Boston, 508 p.

Calculated viscosity, dry
[Pas]

Info Log base 10 of the liquid viscosity in Pas (Pascal seconds), calculated assuming a dry magma and the crudely estimated liquidus temperature given below. From McBirney, A.R., 1993, Igneous Petrology, Second Edition. Appendix B, in, Jones and Bartlett Publishers, Boston, 508 p.

Calculated viscosity, wet
[Pas]

Info Log base 10 of the liquid viscosity in Pas (Pascal seconds), calculated assuming a wet magma and the crudely estimated liquidus temperature given below. %H2O in the magma was estimated as described below under "estimated H₂O content". From McBirney, A.R., 1993, Igneous Petrology, Second Edition. Appendix B, in, Jones and Bartlett Publishers, Boston, 508 p.

Estimated liquidus temp.
[°C]

Info Calculated using a linear equation that assumes liquidus temperatures of 1250 °C for magmas with 48% SiO₂ and 700 °C for magmas with 78% SiO₂: Temp = (-18.33 * SiO₂%) + 2130. This value is only used for liquid density and viscosity calculations. Do not use for petrogenetic purposes.

Estimated H₂O content
[wt. %]

Info This estimate is based on medium-pressure plutonic rocks, and is a 4th order polynomial fit through a set of assumed values that are based on silica content. The polynomial is fit through the following %SiO₂/%H₂O points: 35/0.1, 40/0.1, 45/0.2, 50/0.4, 55/0.8, 60/1.6, 65/2.8, 70/3.9, 75/5.0, and 78/6.0. This value is for wet magma viscosity calculations only and should not be used for petrogenetic purposes.


Classification after Streckeisen

This function allows the classification of your rock using the Streckeisen-Diagram (QAPF-Diagram). Please indicate first whether your rock is volcanic or plutonic.

My sample is a ...


The Streckeisen- (QAPF-) diagram

Download Streckeisen Diagram

Explanations

Q:

The quartz content in wt% of the norm.

A:

The orthoclase content in wt% of the norm.

P:

The plagioclase (albite and anorthite) content in wt% of the norm.

F:

The content of nepheline and leucite in wt% of the norm.


Index

Volcanic rocks

Plutonic rocks

1

Quartz Alkali-Feldspar Rhyolite

Quartzolite

2

Rhyolite

Quartz-Rich Granitoid

3

Dacite

Alkali-Feldspar Granite

3a

Plagidacite (Quartz-Andesite)

4

Quartz-Bearing Alkali-Feldspar Trachyte

Syeno-Granite

5

Quartz-Trachyte

Monzo-Granite

6

Quartz-Latite

Granodiorite

7

Basalt, Andesite

Tonalite

7a

Quartz-Bearing Latite-Andesite, Quartz-Bearing Latite-Basalt

7b

Andesite, Quartz-Basalt

7c

Latite-Andesit, Latite-Basalt

7d

Andesite, Basalt

7e

Foid-Bearing Latite-Andesit, Foid-Bearing Latite-Basalt

7f

Foid-Bearing Andesite, Foid-Bearing Basalt

8

Alkali-Feldspar Trachyte

Quartz-Bearing Alkali-Feldspar Syenite

9

Trachyte

Quartz-Syenite

10

Latite

Quartz-Monzonite

11

Foid-Bearing Alkali-Feldspar Trachyte

Quartz-Monzodiorite, Quartz-Monzogabbro

12

Foid-Bearing Trachyte

Quartz-Diorite, Quartz-Gabbro, Quartz-Anorthosite

13

Foid-Bearing Latite

Alkali-Feldspar Syenite

14

Phonolite

Syenite

15

Tephritic Phonolite

Monzonite

16

Phonolitic Basanite (Olivine > 10%), phonolitic Tephrite (ol < 10%)

Monzodiorite, Monzogabbro

17

Basanite (Olivine > 10%), Tephrite (ol < 10%)

Diorite, Gabbro, Anorthosite

18

Phonolitic Foidite

Foid-Bearing Alkali-Feldspar Syenite

19

Tephritic Foidite

Foid-Bearing Syenite

20

Foidite

Foid-Bearing Monzonite

21

Foid-Bearing Monzodiorite, Foid-Bearing Monzogabbro

22

Foid-Bearing Diorite / Gabbro / Anorthosite

23

Foid Syenite

24

Foid Monzosyenite

25

Foid Monzodiorite, Foid Monzogabbro

26

Foid Diorite, Foid Gabbro

27

Foidolite



Classification with the TAS diagram

This function allows the classification of your rock using the TAS-Diagram (Total Alkali vs. Silica).

The TAS Diagram

Download TAS Diagram

Explanations

Usually, this diagram is only used for volcanic rocks. Accordingly, only the names of the corresponding volcanic rocks are given here.

Index

Volcanic rocks

Pc

Picrobasalt

B

Basalt

O1

Basaltic andesite

O2

Andesite

O3

Dacite

R

Rhyolite

S1

Trachybasalt

S2

Basaltic trachyandesite

S3

Trachyandesite

T

Trachyte or Trachydacite

U1

Basanite or Tephrite

U2

Phonotephrite

U3

Tephriphonolite

Ph

Phonolite

F

Foidite


Download my data

Current date:

Enter a title for the currrent data-set

Identification: Sample number, etc.

Download a file with the results

The Streckeisen- and TAS-classifications can be downloaded using the Buttons below the diagrams.


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