Mica
Mica group
Common · K(Al,Mg,Fe,Li)₂₋₃(Si,Al)₄O₁₀(OH,F)₂
A group of sheet silicates with perfect basal cleavage yielding flexible, elastic flakes. Forms in granites, pegmatites, and metamorphic schists. Its reflective flakes account for the sparkle in many metamorphic rocks.
Identity
- Formula
- K(Al,Mg,Fe,Li)₂₋₃(Si,Al)₄O₁₀(OH,F)₂
- Chemical class
- Silicate
- Members
- Muscovite, Phlogopite, Annite
- Also known as
- White mica (muscovite and its kin), Black mica (biotite)
Crystallography
- Crystal system
- Monoclinic
- Habits
- Foliated, Tabular, Massive
- Fracture
- Uneven
Physical properties
- Mohs hardness
- 2.5
- Density
- 2.83 g/cm³
- Luster
- Pearly, Vitreous
- Colors
- colorless, white, gray, brown, green, black
- Streak
- white
- Transparency
- Transparent, Translucent
Geology
- Origins
- Igneous, Metamorphic
- Host rocks
- Granite, Schist and gneiss
- Associated minerals
- Quartz, feldspar, Tourmaline, Garnet
- Found in
- Diorite, Gneiss, Granite, Pegmatite, Rhyolite, Sandstone, Schist, Slate, Pegmatite deposit
- Geography
- worldwide
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- Mica Group. Mindat.org (Hudson Institute of Mineralogy).
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Muscovite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Biotite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Phlogopite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Lepidolite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Muscovite. Mindat.org (Hudson Institute of Mineralogy).
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