Here’s the Wiki link.

Basically *, olivine is a high temperature / high pressure silicate mineral, so it is quite happy sucking up the silicate in the mantle and mafic igneous rocks (basalt, gabbro, etc.) Which are pretty much the majority of this planet, and, I’d assume, all the other stuff in this part of the solar-system. It’s got a nice compact structure of silica tetrahedrons which makes it sturdy. Felsic igneous rocks (granite, rhyolite, etc) are more rare in the solar system as they need plate tectonics (for the most part) to form and almost never contain olivine – the lower temps and pressures favor other silicate minerals like pyroxene, amphibole, etc.. There are exceptions, naturally.

Here on earth, with all of our water, olivine breaks down pretty fast into other lower temperature minerals. In the abscence of water, olivine is really stable over a wide range of temperature and pressure.

*heh, geology pun.

(Edited)