Mica (Muscovite/Phlogopite) in Matrix
Muscovite / Phlogopite (Phyllosilicate Group) · Mineral Specimen / Industrial Mineral
Crystal System
Monoclinic; typically occurs as platy, foliated, or micaceous masses and pseudohexagonal crystals.
Mineral Group
Silicates (Subgroup: Phyllosilicates / Mica Group)
Chemical Formula
KAl2(AlSi3O10)(OH)2 (Muscovite) or KMg3(AlSi3O10)(OH)2 (Phlogopite)
Formation Process
Primarily Metamorphic (schists and gneisses) or Igneous (pegmatites and granites) involving high pressure and fluid interaction.
About This Crystal
The specimen features flaky, platy minerals with a distinct pearly to metallic luster embedded in a rocky, earthy matrix. The mica flakes appear silvery, brownish, or golden, exhibiting a characteristic layered ('book') structure and high reflectivity.
Physical Characteristics
Color: Silvery-white to golden-brown; Streak: White; Cleavage: Perfect basal (one direction) into thin flexible sheets; Specific Gravity: 2.76–3.0; Fluorescence: Generally none.
Optical Properties
Biaxial negative; Refractive Index 1.55–1.61; exhibits pearly luster on cleavage faces and vitreous luster elsewhere.
Hardness & Durability
Origin Region
Worldwide; notable sources in India, Brazil, Russia, and the USA (pegmatites and metamorphic schists).
Hardness & Durability
Mohs Hardness: 2.5–4.0; Very soft and easily scratched; toughness is low as flakes can be peeled or bent.
Care & Maintenance
Extremely fragile; avoid ultrasonic cleaning or chemicals. Clean with a soft, dry brush only. Store away from harder minerals to prevent surface abrasion.
Rarity & Value
Common; value is generally low for small matrix specimens, though large, clear 'mica books' are valued by collectors.
Special Characteristics
Perfect basal cleavage allows it to be split into paper-thin, transparent, flexible sheets. Excellent thermal and electrical insulator.
Lore & History
Historically used as 'Muscovy glass' for windows in Russia before glass was affordable. Metaphysically associated with mental clarity and self-reflection (the 'mirror to the soul').