Talc
Image: John Krygier (Public domain)
Mineral NameTalc
Chemical FormulaMg₃Si₄O₁₀(OH)₂
Mohs Hardness1
Crystal Systemmonoclinic
Lusterpearly
Streak Colorwhite
CleavagePerfect basal cleavage on {001}
Fractureuneven
Specific Gravity2.7
Colorswhite, gray, pale green, yellowish, brownish
Transparencytranslucent
Type LocalityPietranera, Rovegno, Genova Province, Liguria, Italy
Mineral GroupSilicates
Usescosmetics, ceramics, paint filler, paper, carving stone
Associated Mineralsserpentine, chlorite, dolomite, magnesite, tremolite
Raritycommon
Description
This specimen displays talc in a botryoidal (grape-like) habit, characterized by its soft, greasy feel and typically pale coloration. The surface shows a pearly luster on the rounded forms.
Geological Context
Talc is a metamorphic mineral formed from the alteration of magnesium-rich rocks such as serpentinites and dolomitic marbles under low-grade metamorphic conditions. It is a common product of hydrothermal alteration.
