I'm a senior Chemical Engineering student at Clemson University and I can't seem to find a decent definition. In the case of peridotite to serpentine, the process actually involves a reduction in heat and pressure.
Peridotite starts out as a sub-crustal, upper mantle rock.
No, I'm not mixing up rocks and minerals. Click here for some additional information from my GeoTour to the serpentinites of the Josephine Ophiolite. Hope this helps, and good luck with your studies. If you need any additional information, you know how to reach me.