Seawater seeps down into the mantle and heats up. As the seawater hits the minerals, the olivine and pyroxene within the periodite turn into serpentine minerals and produce hydrocarbons.

The meteorite mainly consists of olivine (Fa24.6), low-Ca pyroxene (Fs20.5), and troilite and Fe-Ni metal, with minor amounts of feldspar (Ab82.4-84.7). Three poorly metamorphosed porphyritic ...

However, looking at light reflected by the asteroid to deduce its composition – rich in pyroxene but low in olivine – revealed that it does match samples from the moon collected by the Apollo ...

In this case the olivine crystals formed early in the crystallization history but also at elevated temperatures. Pyroxene oikocrysts show distinct zoning from pigeonite to augite, i.e. from Ca-rich ...