Feldspars (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8) are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust.[1] Feldspars crystallize from Magma in both intrusive and extrusive igneous rocks, as veins, and are also present in many types of Metamorphic rock. Rock formed almost entirely of calcic Plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of Sedimentary rock..
It is for pottery, and is formed when metamorphic rocks are formed by lava, and some of the metamorphic rock crystallizes. Feldspar is quite a common mineral, and it makes up about 60% of the Earths' crust. Feldspar and sometimes forms into small square shapes. Feldspar crystallizes from magma forming in certain rocks. Feldspar is usually a reddish color such as pink or red.
Feldspar is derived from the German word "Feld", which means field, and Spat, which is a non-ore rock. The term, "Feldspathic" is used to refer to objects that contain feldspar.