Feldspaattien

Feldspaattien, commonly known as feldspars, are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight. They are the most common group of minerals in the Earth's crust. Feldspars are essential components of igneous, metamorphic, and sedimentary rocks. They are characterized by their aluminum silicate framework with varying amounts of potassium, sodium, and calcium.

The feldspar group is broadly divided into two main series: the alkali feldspars and the plagioclase feldspars. Alkali feldspars are a solid solution series between albite (sodium feldspar) and orthoclase or microcline (potassium feldspar). Plagioclase feldspars are a solid solution series between albite (sodium feldspar) and anorthite (calcium feldspar). The specific proportions of sodium, potassium, and calcium determine the exact mineral within these series, such as sanidine, anorthoclase, orthoclase, microcline, albite, oligoclase, andesine, labradorite, bytownite, and anorthite.

Feldspars exhibit a wide range of colors, including white, pink, gray, and even green, depending on their chemical composition and the presence of impurities. They typically have a Mohs hardness of 6 to 6.5 and a specific gravity of 2.55 to 2.76. They cleave in two directions at nearly right angles.

In industry, feldspar is extensively used in the manufacturing of glass, ceramics, and as a filler in paints, plastics, and rubber. Its fluxing properties make it valuable in glass and ceramic production by lowering the melting point of silica. In geology, the weathering of feldspars is a significant source of clay minerals.