Tags: Chemical Substance, Mineral.
Sanidine is the high temperature form of potassium feldspar (KNa)(SiAl)4O8. Sanidine most typically occurs in felsic volcanic rocks such as obsidian rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system. Orthoclase is a monoclinic polymorph stable at lower temperatures.
