Natural Indian Minerals
Feldspar Minerals

Name and Composition - Orthoclase: K (AISi3O8) (potassium aluminium silicate); Albite: Na(AISi3O8) (sodium aluminum silicate); Anorthite: Ca(AISi3O8) (calcium aluminium silicate).

Physical Properties - It occurs in variable coloures, usually white or light coloured but orthoclase is often pink or reddish. Ca-rich plagioclase is often dark grey coloured with bluish tinge; sometimes greenish or bright green (microcline) or colourless. Crystals are prismatic and twinning is a common feature. Luster is vitreous to pearly; iridescence may be seen on cleavage face. Hardness is 6.02 to 6.5; sp. gr. is 2.56 to 2.63.

Mode of Occurrence - Found associated with quartz in pegmatites.

Uses - Feldspar is used as flux in ceramic industries and for welding electrodes. It finds use in glass industries, acid proof refractory's; as mild abrasive in scouring powder; as functional fillers in paint, plastic, rubber and adhesives; as a bonding agent in abrasives; in manufacture of artificial teeth, fertilizer and white cement. Certain varieties of feldspar like moonstones are used as semi precious stones.

Mineral based Industries – Glass and ceramic industries, pulverisers.

Industrial Prospects – Glass and ceramic industries, pulverisers.


Physical Properties
Hardness
Sp. gr.
Reflectance
Density
6.02 to 6.5
2.56 to 2.63
88 - 97
2.65 g/cm3
Chemical Properties
Silica Oxide (SiO2)
Alumina Oxide (Al2O3)
Ferric Oxide (Fe2O3)
Titanium Oxide (TiO2)
Sodium Oxide (Na2O)
Potash Oxide (K2O)
Loss on Ignition
67.50%
18.00%
0.12%
0.04%
2.50%
11.00%
0.40%
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