Serpentinite
Image: James St. John (CC BY 2.0)
Mineral NameSerpentinite
Chemical Formula(Mg,Fe)₃Si₂O₅(OH)₄
Mohs Hardness2.5
Streak Colorwhite
Cleavagepoor to none
Fractureuneven/splintery/conchoidal
Specific Gravity2.6
Colorslight green, dark green, yellowish-green, blackish-green, brownish-green
Transparencytranslucent/opaque
Type LocalityRed Lodge Chromite District, Rock Creek Canyon, Beartooth Mountains, Montana, USA
Mineral GroupSilicates
Usesdecorative stone, carving material, industrial, collector
Associated Mineralsmagnetite, chromite, olivine, pyroxene, talc, brucite, magnesite
Raritycommon
Description
The image shows a mottled green rock with lighter yellowish-green areas and darker greenish-black patches, exhibiting a somewhat massive and textured appearance.
Geological Context
Serpentinite forms through the hydrothermal alteration (serpentinization) of ultramafic igneous rocks like peridotite and dunite, often in metamorphic settings. This sample is from a Precambrian chromite district, indicating its formation from ultramafic protoliths rich in chromium.
