Pretty much everywhere. When a feldspar cools, it may segregate internally into separate mineral crystals, one type oriented within the other according to the symmetry of the host crystal. The Australian production about 94 000 t/year is dominated by Western Australia. Feldspar - Feldspar - Uses: Feldspars are used widely in the glass and ceramics industries. Some of the most common minerals in the earth include quartz, mica, olivine, feldspar, amphibole and pyroxene. World mine production is about 23 Mt/year with Turkey (30%) and Italy (20%) being the major producers. Roughly 60 percent of the earth's crust is composed of feldspar. Quartz is made of silicon dioxide, a mineral most often identified as grains of sand on a beach or in a desert. About 60% of the earth's crust is feldspar.feldspar is found near volcanoes.because it it a type of igneous rockFeldspar if found mostly in Italy, Turkey and China (Credit: Scott Horvath, USGS. Although quartz is more abundant in the earth's crust than any single feldspar mineral, the feldspar group exceeds quartz in abundance. Alkali feldspars are more commonly used commercially than plagioclase feldspars. In addition to this, ~50 000 t/year of a quartz–feldspar blend are produced for use in glassmaking by crushing granite near Beechworth, Victoria. Microcline is the stable form below about 400 C. Orthoclase and sanidine are stable above 500 C and 900 C, respectively. Feldspar - Feldspar - Chemical composition: All the rock-forming feldspars are aluminosilicate minerals with the general formula AT4O8 in which A = potassium, sodium, or calcium (Ca); and T = silicon (Si) and aluminum (Al), with a Si:Al ratio ranging from 3:1 to 1:1. It is undoubtedly the most important rock-forming mineral group in nature. The feldspar-rich rocks larvikite and a few anorthosites are employed as both interior and exterior facing slabs. Albite, or soda spar as it is known commercially, is used in ceramics. Potassium feldspar comes in three different crystal structures that depend on the temperature it formed at. The feldspar group of minerals is unusual among gemstones which are usually considered the rarest of objects, for as a group, feldspar is the most common mineral known to man. Feldspar comes in many different varieties, as this mineral describes seven major blends of elements. Public domain.) Mineral: Feldspar Primary Commodity: Feldspar Primary Commodity Uses: Feldspar is one of the most common minerals on the planet and is mostly used for glassmaking and ceramics. Feldspars are aluminosilicates containing varying amounts of calcium, potassium, or sodium. Outside the geological community, only dedicated mineral collectors can tell these apart.