Wadsleyite
Wadsleyite is a high-pressure form of olivine found in shock veins in meteorites and deep in Earth's mantle.
Wadsleyite has the same chemistry as olivine, magnesium iron silicate, but its atoms are packed more tightly. It was predicted from laboratory experiments and named after the crystallographer Arthur David Wadsley, then found in nature in the Peace River L6 chondrite from Canada in 1983.
In meteorites, wadsleyite forms when a collision between asteroids squeezes olivine to pressures of roughly 13 to 20 gigapascals inside hot shock veins. The pressure lasts only seconds or less, so the new mineral survives only where the rock cooled quickly enough to freeze it in place. It often sits alongside ringwoodite, a still denser form.
On Earth, wadsleyite is believed to make up much of the mantle between about 410 and 520 kilometres deep, so meteorites provide rare natural samples of material that otherwise cannot be reached. Its grain size in a shock vein helps scientists estimate how long the impact pressure lasted.
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