When I started studying impact events, there is a polymorph of silica (sand) quratz that fascinated me. It is an extremely dense form of common silica, but can only form under extreme pressure, called Stishovite. The bedrock over at Kaali is dolomite, but if there is any sand out there, chances are they might have converted to Stishovite.

It always fascinated me that how extreme pressure can change the most common mineral on earth's crust to a completely different form!

Stishovite is common in moon :)