Wollastonite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameWollastonite
Chemical FormulaCaSiO3
Mohs Hardness4.5
Crystal Systemtriclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {100}, good on {001} and {102}
Fractureuneven
Specific Gravity2.9
Colorswhite, grey, pale green, pale brown, colorless
Transparencytranslucent
Type LocalityTranomaro-Maromby area, Amboasary District, Anosy (Fort Dauphin) Region, Tuléar (Toliara) Province, Madagascar
Mineral Groupsilicates
Usesindustrial filler, ceramic raw material, metallurgical flux
Associated Mineralsgarnet, diopside, vesuvianite, calcite, quartz
Rarityuncommon
Description
This specimen displays a large, blocky aggregate of fibrous to bladed wollastonite crystals, predominantly off-white to light grey with some yellowish-brown areas. The characteristic fibrous texture is clearly visible, exhibiting a vitreous to pearly luster on cleavage surfaces.
Geological Context
Wollastonite typically forms in contact metamorphic rocks, particularly in metamorphosed impure limestones or calc-silicate skarns, where silica-rich fluids react with calcium carbonate.
