Polished K Feldspar-Epidote-Quartz-Biotite Matrix
$19.00 – $400.00Feldspars are a group of rock-forming tectosilicateminerals that make up about 41% of the Earth‘s continental crust by weight.[2]
Feldspars crystallize from magma as veins in both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock.[3] Rock formed almost entirely of calcic plagioclase feldspar (see below) is known as anorthosite.[4] Feldspars are also found in many types of sedimentary rocks.[5]