Peridot from Deep Inside the Earth’s Mantle

and ejected by volcanism in Pakistan. Only Peridot and certain diamonds, like the boron-blue Hope Diamond, come from this deep in the Earth. We have never drilled to the mantle, so these minerals brought from below are our only samples. The green peridot crystals are also seen in certain meteorites that came from planets and planetoids older than Earth itself. Examples below, with similar orthorhombic cleavage across several celestial bodies formed independently.

The peridot comes from slowly cooling magma melt, a viscous flow taking one billion years to circulate on Earth. It is brought to the surface as a volcanic eruption, sometimes as a volcanic “bomb” or as a cataclysmic collision in space between planetoids or proto-planets destroyed before the Earth formed.

My Earth sample is 193Ct. From UT: “Crystals very rare… Unlike most other gems, olivine is highly susceptible to chemical weathering and thus does not survive very long at the surface in wet climates. This fact probably accounts for the very limited number of known gem localities”