Peridotite
Image: James St. John (CC BY 2.0)
Mineral NamePeridotite
Chemical FormulaPrimarily magnesium-iron silicates (olivine and pyroxene)
Mohs Hardness5
Lustervitreous
Streak Colorcolorless to pale green
CleavageVariable (poor in olivine, good in pyroxene)
Fractureuneven
Specific Gravity3.3
Colorsyellowish-green, dark green, black
Transparencytranslucent
Type LocalityBaja California, Mexico
Mineral GroupIgneous rock (ultramafic)
Usessource of chromium, nickel, platinum group elements, scientific research
Associated Mineralsolivine, pyroxene, chromite, magnetite, garnet
Rarityuncommon
Description
A coarsely-crystalline rock dominated by bright yellowish-green olivine crystals, with interspersed darker, often black, accessory minerals.
Geological Context
Peridotites are ultramafic intrusive igneous rocks that form deep within the Earth's mantle. They are brought to the surface through tectonic processes, often found in ophiolite complexes or as xenoliths in volcanic rocks.
