Zinnwaldite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameZinnwaldite
Chemical FormulaK(Li,Fe2+)Al(AlSi3)O10(OH,F)2
Mohs Hardness2.5
Crystal Systemmonoclinic
Lusterpearly
Streak Colorwhite
Cleavageperfect on {001}
Fractureuneven
Specific Gravity2.9
Colorsgreenish-gray, brownish-green, silvery-gray
Transparencytranslucent
Type LocalityCinovec (Zinnwald), Erzgebirge, Bohemia, Czech Republic
Mineral GroupSilicates (Mica Group)
Usescollector, source of lithium (historically)
Associated Mineralsquartz, topaz, cassiterite, wolframite, fluorite
Rarityuncommon
Description
This specimen displays greenish-gray to brownish-green platy crystals of zinnwaldite, forming radiating aggregates with a distinct pearly luster, set on a matrix.
Geological Context
Zinnwaldite is a lithium-iron mica typically found in greisens, pegmatites, and high-temperature hydrothermal veins associated with granitic intrusions, often indicating tin-tungsten mineralization.
