Diopside
Diopside is a calcium-magnesium clinopyroxene found in CAIs, aubrites and many chondrites.
Diopside is a clinopyroxene made of calcium, magnesium, silicon and oxygen, CaMgSi2O6. Nearly iron-free diopside is pale green or colourless.
In meteorites it appears in several settings. It forms rims and layers around calcium-aluminium-rich inclusions, the oldest solids in the Solar System, and is part of the sequence of minerals that condensed as the solar nebula cooled. Aluminium- and titanium-bearing diopside, once called fassaite, is a major mineral inside some CAIs. Diopside also occurs in aubrites and enstatite chondrites, which formed in very oxygen-poor conditions, and as small grains in equilibrated ordinary chondrites, where it grew during heating.
Chromium-rich diopside is a gem mineral on Earth, but the meteorite variety is usually far too small to see without a microscope. Its presence and chemistry help scientists judge temperature and oxygen levels in the environment where a meteorite formed.
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