Peridotite
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Mineral NamePeridotite
Chemical Formula(Mg,Fe)2SiO4 (olivine) + (Mg,Fe)SiO3 (pyroxene)
Mohs Hardness6
Streak ColorWhite to pale green/gray
CleavageNot applicable (rock); constituent minerals like pyroxenes have distinct cleavage
FractureUneven to conchoidal
Specific Gravity3.1
Colorsdark green, greenish-black, yellowish-brown, purple
TransparencyOpaque
Type LocalityUgelvik Peridotite-body, Otrøy, Western Gneiss Region, Caledonides, Norway
Mineral GroupUltramafic Igneous Rock
Usesscientific study, source of chromium and nickel (if mineralized), decorative stone
Associated Mineralsolivine, orthopyroxene, clinopyroxene, pyrope, chromite, magnetite
Raritycommon
Description
This image displays a weathered peridotite rock with a yellowish-brown matrix, featuring numerous small, dark purple pyrope garnet porphyroblasts, with a 1 euro coin providing scale.
Geological Context
Peridotite is an ultramafic igneous rock, primarily found in the Earth's mantle and the lower parts of oceanic crust. It forms by crystallization from magma or by metamorphism of existing mantle rocks, often brought to the surface in ophiolites or as xenoliths in volcanic pipes.
