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Halite

Halite
Selpologne.jpg
Halite from the Wieliczka salt mine, Małopolskie, Poland
General
Category Halide mineral
Formula
(repeating unit)
NaCl
Strunz classification 3.AA.20
Crystal system Cubic
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space group Fm3m
Unit cell a = 5.6404(1) Å; Z = 4
Identification
Formula mass 58.433 g/mol
Color Colorless or white
Crystal habit Predominantly cubes and in massive sedimentary beds, but also granular, fibrous and compact
Cleavage Perfect {001}, three directions cubic
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness 2.0 - 2.5
Luster Vitreous
Streak White
Diaphaneity Transparent
Specific gravity 2.17
Optical properties Isotropic
Refractive index n = 1.544
Solubility Water-soluble
Other characteristics Salty flavor, Fluorescent
References

Halite (pronunciation: /ˈhælt/ or /ˈhlt/), commonly known as rock salt, is a type of salt, the mineral form of sodium chloride (NaCl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount and type of impurities. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates.

Halite occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, playas, and seas. Salt beds may be hundreds of meters thick and underlie broad areas. In the United States and Canada extensive underground beds extend from the Appalachian basin of western New York through parts of Ontario and under much of the Michigan Basin. Other deposits are in Ohio, Kansas, New Mexico, Nova Scotia and Saskatchewan. The Khewra salt mine is a massive deposit of halite near Islamabad, Pakistan. In the United Kingdom there are three mines; the largest of these is at Winsford in Cheshire producing on average a million tonnes per year.


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