feldspar

Feldspar is a general term for feldspar rocks. It is a type of aluminosilicate minerals containing calcium, sodium and potassium. It is the most common mineral in the earth's crust, with a ratio of 60%, which can be found in igneous rocks, metamorphic rocks and sedimentary rocks. Feldspar is the main mineral composition of almost all igneous rocks, and is of great significance for classification of rocks. Feldspar isomorphic substitution is very developed. Their chemical composition is commonly expressed as OrxAby Anz (x + y + Z = 100). Or, Ab and An represent KAlSi3O8, NaAlSi3O8 and CaAl2Si2O83 components respectively. Based on a two component, it can be divided into two isomorphic series: alkaline feldspar series (Or-Ab Series); plagioclase series (Ab-An Series). The mixture of Or and An can be miscible only and does not form a series.
The basic structural unit of feldspar is tetrahedron. It consists of 4 oxygen atoms surrounded by a silicon atom or aluminum atom. Each tetrahedron shares an oxygen atom with another tetrahedron, forming a three-dimensional skeleton. The large radius of alkali or alkaline earth metal cations is located in the large gap within the skeleton, and the coordination number is 8 (in the monoclinic feldspar) or 9 (in the three diagonal feldspar). Feldspar crystals are mostly columnar or columnar along a crystalline axis. Twinning is very common. There are more than 20 kinds of twin crystals. Common are sodium long stone law, the law of man's law, Bawinno's law, and the double crystal of Xiao Na Chang Shi law. They are found in three oblique crystals or monoclinic and three oblique crystals respectively. Feldspar is often milky white, but it is often dyed with yellow, brown, light red, dark grey and so on. Some can also have beautiful color change or color. There are two groups of cleavage, with an angle of 90 degrees (monoclinic) or near 90 degrees (87 degrees) (three diagonal system). The proportion between 2.56 and 2.76 increased with the increase of An content and decreased with the increase of Or. The moth hardness is 6 ~ 6.5. The feldspar rich in potassium or sodium is mainly used in the ceramic industry, the glass industry and the enamel industry. The feldspar containing rare elements such as rubidium and cesium can be used as a mineral material for the extraction of these elements, and the beautiful feldspar of color can be used as a decorative stone and a secondary gem.
The most common mineral in the earth's crust is feldspar, which is also found on the moon and meteorites. Within the depth of 15 km underground, feldspar accounts for 60% of the total crustal weight. Feldspar is the main constituent of igneous rock, and is also common in metamorphic rocks and sedimentary rocks. Feldspar is a kind of aluminosilicate mineral containing calcium, sodium and potassium. It has many kinds, such as albite, calcite, barium feldspar, barium feldspar, micro plagioclase, ortho feldspar, and feldspar. They all have glassy luster, various colors, colorless, white, yellow, pink, green, gray, black and so on. Some are transparent and some are translucent. Feldspar itself should be colorless and transparent. It is colored or not completely transparent because it contains other impurities. Some are lumpy, some are plate shaped, some are columnar or needle shaped. Usually in igneous rocks and metamorphic rocks, the feldspar is very small, only 0.1 to 10 millimeters, up to 5~10 centimeters in the porphyry, and some in the pegmatite of some tens of meters. Feldspar is a raw material for ceramics and glass industry. Some feldspars have beautiful colourful or faint colors, and can be used as gem materials.