perhaps with all those crystals laying around some of the moutains started as a some small crystals that crystalized toghether till it became one big crystall poping out of the ground, and then after centuries(?) of erosion and sedimentention it became what we see today
but of course the gods perhaps could have just skipped all those steps and create the moutains as they are right now
being the mountains originally a crystal, and perhaps still having a crystal core could explain why some of them not looking so un-earthlly to us, several crytals generate complicated geometrical patterns as the \"grow\"