Appearance
Their main constituents are silica and alumina, but their potassium, calcium, and sodium contents vary. They have an opaque and transparent sheen and come in a variety of hues, including colorless, white, gray, brown, yellow, and green.
Geographical Distribution
It has been discovered in several meteorites and on the moon. It also comprises about 60% of the crust of the Earth. Feldspars can be found throughout the whole rock cycle. Since feldspars frequently precipitate out of cooling magma, a large number of feldspars are igneous.
History
Johan Gottschalk Wallerius gave Feldspar its official name in 1747. Because some of the earliest specimens were discovered in fields, the term is a truncation of the lengthier fieldspar. Any non-metallic mineral with a vitreous (glassy) luster that fractures on distinct flat surfaces is referred to as spar in general.
Chemical Composition
Tectosilicates belong to this class of minerals. Three endmembers can be used to indicate the compositions of the main elements in common feldspars: potassium feldspar (K-spar) endmember KAlSi3O8, albite endmember NaAlSi3O8, and anorthite endmember CaAl2Si2O8.
Types
Some feldspar are following:
- Albite
- Amazonite
- Andesine
- Anorthite
- Anorthoclase
- Banalsite
- Buddingtonite
- Bytownite
- Celsian
- Dmisteinbergite
- Filatovite
- Hexacelsian
- Hyalophane
- Kokchetavite
- Kumdykolite
- Labradorite
- Microcline
- Oligoclase
- Orthoclase
- Paracelsian
- Reedmergnerite
- Rubicline
- Sanidine
- Slawsonite
- Stronalsite
- Svyatoslavite
Uses
Feldspar is a common raw material used in ceramics and glassmaking, and it is also occasionally used as an extender and filler in paint, rubber, and plastics. Alumina derived from feldspar enhances the hardness, durability, and resistance to chemical corrosion of glass products. The alkalis in feldspar—sodium, potassium, and calcium oxides—work as a flux in ceramics, bringing down the melting point of a mixture. Early in the firing process, fluxes melt and create a glassy matrix that binds the device’s other components together.
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