Associated minerals include garnets, vesuvianite, diopside, tremolite, epidote, plagioclase feldspar, pyroxene and calcite. The mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene. Rhyolite tuffs contain pumiceous, glassy fragments and small scoriae with quartz, alkali feldspar, biotite, etc. They are granite with granophyric quartz, perthitic potassium feldspar, biotite and magnetite. It can be found in igneous rocks containing potassium feldspar and plagioclase. Anorthite is the calcium endmember of the plagioclase feldspar mineral series. Albite is considered both a plagioclase and alkali feldspar. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Luminescence dating techniques observe 'light' emitted from materials such as quartz, diamond, feldspar, and calcite. Granite is a felsic rock, meaning it is rich in potassium feldspar and quartz. Solid solutions between K-feldspar and albite are called "alkali feldspar". Hard-paste now chiefly refers to formulations prepared from mixtures of kaolin, feldspar and quartz. Most common rock-forming minerals are anisotropic, including quartz and feldspar. Commodities such as black granite, corundum, and feldspar are also found. Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group.