Orthoclase is a mineral that belongs to the family of silicate minerals called feldspar. The deference between the feldspars and the other silicates is that the former contain a mixture of the following chemical elements: Potassium K, Calcium Ca and Sodium Na, in addition to the usual constituents of the quartz based minerals, such as Aluminum, Al, silicon Si and oxygen O.
The other related crystals from this family are the attractive labradorite, moonstone, sunstone, and amazonite. Orthoclase crystal, as its name already indicates, is a member of the orthoclase feldspars, The most important feature of this class is that they contain K and Na, in contrast to Ca and Na contained in the plagioclase.
A typical orthoclase is a solid solution of KAlSi3O8 and albite NaAlSi3O8. The origin of its name is probably from the Greek name for e or transparent. The golden variation can be found on Madagascar and in Mexico. The other colors are more frequent. If of gemstone quality orthoclase resembles golden or yellow beryl, also known as heliodor.
Orthoclase an important mineral for industrial applications. Amongst the other uses, it is a source material for porcelain production. Porcelain (the vitrified ceramic of white color) is produced from a mixture of orthoclase, quartz and kaolin. (sunnyray.org)