The plagioclase ("PLAY-jee-oh- CLASE") and alkali ("AL-kuh-lye") forms of this mineral are prevalent in granite.
Amazonstone ("AM-uh-zon-STONE") and cleavelandite ("Cleveland ite") are members of this group of minerals. Samples of it which show a high opalescence ("OH-puh-LESS-ence") are traded as moonstone, and some with a yellow or orange tint are sold as sunstone. The plagioclase ("PLAY-jee-oh- CLASE") and alkali ("AL-kuh-lye") forms of this mineral are prevalent in granite. Made of aluminum, silicon, and either calcium, sodium, or potassium, for 10 points, name this mineral, number 6 on the Mohs scale of hardness.
Amazonstone ("AM-uh-zon-STONE") and cleavelandite ("Cleveland ite") are members of this group of minerals.
feldspar