Wadsleyite
A high-pressure form of olivine, between olivine and ringwoodite, found in shocked meteorites.
Key facts
- Formula
- (Mg,Fe)2SiO4
- Family
- High-pressure minerals
- Crystal system
- Orthorhombic
- First described
- the Peace River L6 chondrite, 1983
Wadsleyite was first found in nature in 1983 in the Peace River meteorite, an L6 chondrite that fell in Alberta, Canada, in 1963. It is named after David Wadsley, an Australian crystallographer.
What it is
Wadsleyite is another dense form of olivine, stable at somewhat lower pressures than ringwoodite. Its structure can hold water as hydroxyl, which makes it important to ideas about water in Earth's interior.
In Earth's mantle it is thought to be the main mineral between about 410 and 520 kilometres deep, and the change from olivine to wadsleyite produces a sharp boundary that earthquake waves reveal.
Where it is found
It forms in shock veins of strongly shocked ordinary chondrites, often next to ringwoodite. Some grains grew from melt, others from solid olivine.
How it is recognised
It is colourless to pale and very fine-grained. It is identified by Raman spectroscopy or electron diffraction.
Did you know?
The 410-kilometre boundary in Earth's mantle is caused by olivine changing into wadsleyite.
The parent body of the L chondrites suffered a major collision about 470 million years ago, which shocked many of them.