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MicaCalc

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MicaCalc automatically calculates muscovite compositions from microprobe analyses.
The results are presented in tables and in various diagrams (Phengite solid solution series, Mu-Pg-Ce diagram, A'KF diagram, AFM (Ms and Kf) diagram. For further details see below.

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MicaCalc – Muscovite: Composition and classification

Using microprobe analyses, this program can be used to automatically calculate muscovite compositions based on 22 oxygen atoms. The oxides, the cations, the lattice site occupancies, the end members Margarite (CaAl₂)[Si₂Al₂O₁₀](OH)₂), Paragonite (NaAl₂)[Si₃AlO₁₀](OH)₂), Celadonite (K(Mg, Fe²⁺)(Fe³⁺, Al)[Si₄O₁₀](OH)₂) and Muscovite (KAl₂[AlSi₃O₁₀](OH)₂), as well as the values for divalent and trivalent iron are calculated (total iron, Fe²⁺, Fe³⁺).
The micas are classified using the Muscovite-phengite-celadonite diagram, the A'KF diagram (A' = [Al₂O₃+Fe₂0₃]-[Na₂O+K₂O+CaO], K = K₂O, F = Fe0+MgO+MnO) and the AFM (Ms and Kf) diagrams.
Furthermore, the micas are presented in a diagram in which the Si content per formula unit (Si/f.u.) is plotted against the aluminum content per formula unit (Al/f.u.) (based on 11 oxygen atoms). The straight line shown in this diagram represents the Phengite solid solution series. The Si content of muscovite can provide information about the physical conditions during metamorphism (“Phengit Barometer”; see literature).

You can enter the values individually in the table below or use the input fields. Here you enter for up to 5 micas the values (oxides) as rows separated by single spaces (see placeholders; 200 characters max.). Note the order of the elements in the table: Na Mg Al Si K Ca Ti Mn Fe (total Fe as FeO) H₂O Ba Cr! Additionally, the sample designation must come first. You can use the period or the comma as a decimal separator.

If you want, you can delete the example data in the tables first:

Data input

Oxydes: Name Na₂O MgO Al₂O₃ SiO₂ K₂O CaO TiO₂ MnO FeO H₂O BaO Cr₂O₃ Total
(Total Fe as FeO)

Mica 1

Mica 2

Mica 3

Mica 4

Mica 5

Your micas

You can also enter your data (oxides) here (into the light-blue fields).

Name
Oxides Oxides Oxides Oxides Oxides
Na2O
MgO
Al2O3
SiO2
K2O
CaO
TiO2
MnO
FeO
H2O
BaO
Cr2O3
Total
Temperature selection*
Temp. [°C]

* Here you can enter for each mica a temperature (from 500°C to 1100°C max.). This value is used to make a rough pressure estimate with the Phengite barometer. The results are shown in a diagram under "Show Phengite Barometer".

Constants and intermediate results


Oxides [wt.-%] Mol wt. (AW) Mol-Prop. Element Wt.-% Atom-Prop. Oxygen Cations (O=22)
Mica 1
SiO2 Si
TiO2 Ti
Al2O3 Al
Cr2O3 Cr
MgO Mg
CaO Ca
MnO Mn
FeO Fe
BaO Ba
Na2O Na
K2O K
Total* *without Water
Mica 2
SiO2 Si
TiO2 Ti
Al2O3 Al
Cr2O3 Cr
MgO Mg
CaO Ca
MnO Mn
FeO Fe
BaO Ba
Na2O Na
K2O K
Total* *without Water
Mica 3
SiO2 Si
TiO2 Ti
Al2O3 Al
Cr2O3 Cr
MgO Mg
CaO Ca
MnO Mn
FeO Fe
BaO Ba
Na2O Na
K2O K
Total* *without Water
Mica 4
SiO2 Si
TiO2 Ti
Al2O3 Al
Cr2O3 Cr
MgO Mg
CaO Ca
MnO Mn
FeO Fe
BaO Ba
Na2O Na
K2O K
Total* *without Water
Mica 5
SiO2 Si
TiO2 Ti
Al2O3 Al
Cr2O3 Cr
MgO Mg
CaO Ca
MnO Mn
FeO Fe
BaO Ba
Na2O Na
K2O K
Total* *without Water
Mica 1 Mica 2 Mica 3 Mica 4 Mica 5
Grid occupation
Tetrahedron
Tetrahedral Al
Octahedral Al
Octahedron
Interlayer
Total
Check total
Info Compares the sum of the cations (O=22) with the sum of the lattice occupation. These should be equal, so the difference should be 0. Minor deviations can be attributed to rounding errors. Otherwise there may be an analysis error.
The ratio FeO/(FeO+MgO)
FeO/(FeO+MgO)
A´KF
A´
K
F
Total
A´KF (*100)
A´
K
F
Total
AFM (Ms)
A (Ms)
F
M
AFM (Kf)
A (Kf)
F
M

Results
Muscovite (22 oxygens)

Mica 1 Mica 2 Mica 3 Mica 4 Mica 5
SiO2
TiO2
Al2O3
Cr2O3
MgO
CaO
MnO
FeO
BaO
Na2O
K2O
H2O
Total
Cations
Si
Ti
Al
Cr
Mg
Ca
Mn
Fe
Ba
Na
K
Total
The ratio FeO/(FeO+MgO): X(Fe)
X(Fe)
Grid occupation
Si
AlIV
Tetrahedron
AlVI
Cr
Ti
Fetotal (Fe²⁺)
Mn
Mg
Octahedron
Ba
Ca
Na
K
Interlayer
Total
End-members
Margarite
Info Margarite: (CaAl₂)[Si₂Al₂O₁₀](OH)₂)
Paragonite
Info Paragonite: (NaAl₂)[Si₃AlO₁₀](OH)₂)
Celadonite
Info Celadonite: (K(Mg, Fe²⁺)(Fe³⁺, Al)[Si₄O₁₀](OH)₂)
Muscovite
Info Muscovite (KAl₂[AlSi₃O₁₀](OH)₂)
Total
Phengite component in Muscovite
Info The term phengite is generally used for muscovites whose Si/Al ratio is greater than 3:1 and in which the increase in Si is associated with a substitution of Mg²⁺ and Fe²⁺ for Al on the octahedrally coordinated lattice sites (Deer et al., 1992).
Phengite
Muscovite
Total
The Phengite-Celadonite-Muscovite diagram
Paragonite (Pa)
Celadonite (Ce)
Muscovite (Mu)
Total
Fetot., Fe²⁺, Fe³⁺
Fetot.
Fe²⁺
Fe³⁺
The A'KF diagram
A'
K
F
Total
The AFM(Ms) diagram
A (Ms)
F
M
The AFM(Kf) diagram
A (Kf)
F
M
Total
"Phengite barometer"
Al/f.u. (11 O)
Si/f.u. (11 O)
Additional values [pfu]
K+Na+Ca (22 O)
Ti (11 O)
Fe+Mg (22 O)
Na/(Na+K) (22 O)
Na/(Na+K) (11 O)
Mean values (Mica 1–5)
Ø Al (11 O)
Ø Si (11 O)
Min. Si (11 O)
Max. Si (11 O)
Ø Ti (22 O)
Ø Si (22 O)
Min. Ti (22 O)
Max. Ti (22 O)

The Paragonite-Celadonite-Muscovite diagram

Classification of white micas using the Paragonite-Celadonite-Muscovite diagram

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Captions

•

Mica 1

•

Mica 2

•

Mica 3

•

Mica 4

•

Mica 5

Top corner

Paragonite

Right corner

Celadonite

Left corner

Muscovite

"Phengite Barometer"

The white micas in the Si/f.u. vs. Al/f.u. diagram. The straight line shown in this diagram represents the Phengite solid solution series between Muscovite and Celadonite. Higher Si-contents may represent higher formation pressures (see references at bottom of page).

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The Si content of the muscovites plotted against temperature. The lines are isobars. The pressure information is in GPa (after Hermann & Spandler, 2008).

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Captions

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Mica 1

•

Mica 2

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Mica 3

•

Mica 4

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Mica 5

Phengite barometry 2

Pressure-temperature diagram with the isopleths for the Si content per formula unit (Si/f.u.) of the phengites (normalized to 11 oxygen atoms) in the limiting paragenesis with potassium feldspar, phlogopite and quartz. The dashed line shows the stability curve for phengite with 3.3 Si/f.u. according to Velde (1965). The continuous curve at high temperatures marks the upper stability limit of paragenesis. According to Massonne & Schreyer (1987; Fig. 3).

The A'KF diagram

The Micas shown in the A'KF diagram. For infos see captions below. After Ehlers & Blatt (1982).

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Captions

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Mica 1

•

Mica 2

•

Mica 3

•

Mica 4

•

Mica 5

Bottom corner

F = Fe0+MgO+MnO

Red dot bottom corner

Antophyllite, Opx

Dark green field

Chlorite

White dot in dark green field

Almandine

Top right corner

K = K₂O

Purple dot top right corner

K-feldspar

Red dot at end of phengite line

Muscovite

Top left corner

A' = (Al₂O₃+Fe₂0₃)-(Na₂O+K₂O+CaO)

Green dot top left corner

Kyanite, Andalusite, Sillimanite

The AFM(Ms) diagram

The Micas shown in the AFM(Ms) diagram. For infos see below. After Nelson, S.A. (2011).

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Captions

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Mica 1

•

Mica 2

•

Mica 3

•

Mica 4

•

Mica 5

The AFM(Ms) diagram
The AFM(Ms)-diagram

The AFM(Ms) diagram. From Nelson, S.A. (2011).

The AFM(Kf) diagram

The Micas shown in the AFM(Kf) diagram. For infos see below. After Nelson, S.A. (2011).

Download diagram

Captions

•

Mica 1

•

Mica 2

•

Mica 3

•

Mica 4

•

Mica 5

The AFM(Kf) diagram
The AFM(Kf)-diagram

The AFM(Kf) diagram. From Nelson, S.A. (2011).

Download data

Current date

Enter a title

Sample number, etc.

Download data file (*.csv)

Literature

A small, not very current selection. There are also newer publications on this topic on the Internet (e.g.).