High-pressure mineral
A high-pressure mineral is a denser form of a common mineral, created when a collision squeezes rock to extreme pressures.
A high-pressure mineral has the same chemistry as a familiar mineral but a tighter packing of atoms, which forms only under enormous pressure. Examples are ringwoodite and wadsleyite, made from olivine; majorite and akimotoite, made from pyroxene; coesite and stishovite, made from quartz; and diamond, made from graphite.
On Earth such minerals usually form deep in the mantle. In meteorites they form in a flash when asteroids collide. The shock compresses rock for a fraction of a second, and where the rock gets hot enough to melt in thin veins, the new minerals crystallise. They survive only if the rock cools before the pressure drops away.
Finding high-pressure minerals lets scientists estimate how hard a meteorite's parent body was hit, and they also give natural samples of minerals from deep inside planets. They are typically found in black shock veins in heavily shocked L chondrites and Martian meteorites.
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