General Biotite Information
|
 Chemical Formula: |
K(Mg,Fe++)3[AlSi3O10(OH,F)2 |
| Composition: |
Molecular Weight = 433.53 gm |
| |
Potassium 9.02 % K 10.86 % K2O |
| |
Magnesium 14.02 % Mg 23.24 % MgO |
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Aluminum 6.22 % Al 11.76 % Al2O3 |
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Iron 6.44 % Fe 8.29 % FeO |
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Silicon 19.44 % Si 41.58 % SiO2 |
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Hydrogen 0.41 % H 3.64 % H2O |
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Oxygen 43.36 % O |
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Fluorine 1.10 % F 1.10 % F |
| |
- %
F -0.46 % -O=F2 |
| |
______ ______ |
| |
100.00 % 100.00 % = TOTAL OXIDE |
| Empirical Formula: |
KMg2.5Fe2+0.5AlSi3O10(OH)1.75F0.25 |
| Environment: |
Granitic rocks. Forms a series with phlogopite. Has several polytypes (1M, 3T, 2M1). Biotite is now a group name for phlogopite, siderophyllite and eastonite. |
| IMA Status: |
Not Approved IMA 1998 - Bitote is now the group name |
| Locality: |
Common world wide. Link to MinDat.org Location Data. |
| Name Origin: |
Named in 1847 after the French physicist, Jean Baptiste Biot (1774 - 1862), who studied the optical properties of the micas. |
| Name Pronunciation: |
Biotite  |
| Synonym: |
Iron Mica |
| |
Lepidomelane (Fe) |
| |
Manganophyllite (Mn) |
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Micaceous Iron Ore |
| |
Oxybiotite |
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