Damourite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY 3.0)
Mineral NameDamourite
Chemical FormulaKAl₂(AlSi₃O₁₀)(OH)₂
Mohs Hardness2
Crystal Systemmonoclinic
Lusterpearly
Streak Colorwhite
Cleavageperfect basal on {001}
Fractureuneven
Specific Gravity2.8
Colorsgreen, silvery-green, grey-green
Transparencytranslucent
Type LocalityKårarvet (Kararfvet; Korarfvet), Falun, Dalarna, Sweden
Mineral GroupSilicates (Phyllosilicates, Mica Group)
Usescollector, industrial (as muscovite)
Associated Mineralsquartz, feldspar, kyanite, andalusite
Rarityuncommon
Description
A massive, fine-grained aggregate of greenish-grey mica flakes with a distinct pearly to silvery luster, forming a compact rock-like specimen.
Geological Context
Damourite is a fine-grained, compact variety of muscovite, typically formed as an alteration product of other aluminum-rich minerals like feldspar, kyanite, or andalusite in metamorphic rocks.
