Crystal Structure
KAl₂(Si₃Al)O₁₀(OH)₂.
Elemental Composition (by mass)
| Element | Mass % | Visual |
|---|---|---|
| O Oxygen | 43.68% | |
| Si Silicon | 23.00% | |
| Al Aluminum | 22.10% | |
| K Potassium | 10.67% | |
| H Hydrogen | 0.55% |
Computed from simplified end-member formula. Solid-solution series, water content, and trace substitutions cause real-world variation.
IMA Abbreviation (Whitney-Evans 2010)
Ms
→ Muscovite
White mica
Standard symbol from American Mineralogist (Whitney & Evans, 2010). Used in thin-section labeling, phase diagrams, and IMA-style species records.
Pronunciation
/ˈmʌskəvaɪt/
↔ MUSS-kuh-vite
from Muscovy
Tenacity
Behavior:
elastic
Under stress:
Springs back
Same as mica family.
Luster
pearly
Pearly sheen on sheets.
Diaphaneity (Transparency)
transparent-to-translucent
Thin sheets are transparent (historical "Muscovy glass").
Type Locality
(historical Russian "Muscovy glass")
Described 1850 by Dana
› Browse all type localities
Magnetism
Category:
diamagnetic
Test result:
Null or slight repulsion
K-Al mica, no transition metal.
Test with rare-earth magnet (N42 or N52 neodymium). Suspend specimen on thread for sensitive paramagnetic detection. Diamagnetic minerals are weakly repelled (visible only with strong magnets like bismuth).
Specific Gravity
2.77–2.88
g/cm³
light
Light-colored mica.
For comparison: water = 1.00, glass ≈ 2.5, quartz = 2.65, corundum ≈ 4.00, galena ≈ 7.50, gold ≈ 19.3.
Cleavage & Fracture
Cleavage:
perfect 1 direction {001} — basal
Fracture:
uneven
Splits into thin elastic colorless sheets.
Market availability: Common
Widely available in most dealer stocks. Specimens span all price tiers.
Mohs 2–2.5
Vickers (~) 75 HV
Knoop (~) 85 HK
Geological setting
Plutonic igneousPegmatiteMetamorphic
Element composition by mass
Formula: KAl₂(AlSi₃O₁₀)(OH)₂ · molar mass: 398.3 g/mol
| O | 48.2% | |
| Si | 21.15% | |
| Al | 20.32% | |
| K | 9.82% | |
| H | 0.51% |
Computed from atomic weights (IUPAC 2021). Site-occupancy groups (Fe,Mn) split equally.
GroupMica Group
Mohs Hardness
2–2.5
Muscovite sits at 2–2.5 on the Mohs scale — soft enough to be scratched by a fingernail.
Colors:
Streak
White
White
Crystal system
Monoclinic
Monoclinic
SilicatesSilicates (Phyllosilicates — Micas)
TL;DR · 1 min read
Muscovite (KAl₂(AlSi₃O₁₀)(OH)₂) is the most common mica species and a defining sheet silicate. Its name comes from "Muscovy glass" — large transparent Muscovite plates from Russia historically used as windowpanes.
Muscovite (KAl₂(AlSi₃O₁₀)(OH)₂) is the most common mica species and a defining sheet silicate. Its name comes from “Muscovy glass” — large transparent Muscovite plates from Russia historically used as windowpanes. Muscovite forms in granitic pegmatites, schists, and gneisses, where it grows as flexible elastic books reaching meter-scale dimensions.
More minerals to explore
Other Members of the Mica Group
云母族
- Biotite (黑云母)
- Phlogopite (金云母)
- Lepidolite (锂云母)