HALITE MINERAL FACTS Nevada Turquoise gem stones
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Halite Mineral Facts:

Chemical Formula: NaCl - equivalent to common table salt

Colors: Colorless to white when pure.
Halite, when pure, is colorless, but the impurities present often color it red, gray, yellow, purple or blue. The bright blue mottlings observed in many specimens are thought to be due to the presence of colloidal sodium. Its streak is colorless or white.

Hardness: 2 to 2.5

Density: 2.17

Cleavage: The cleavage is perfect parallel to each of the cubic faces.

Crystallography: Cubic
Common crystals in cubes, rarely octahedra; cubes often with hollow faces, giving hopper shaped crystals. Also occurs massive and granular, rarely in fibrous forms.

Luster:.  Luster is vitreous. The mineral is transparent or translucent

Optics: (Refractive Index)  n= 1.5442

Halite salt crystal

Composition, Structure and Associated Minerals:
A common and widely disseminated mineral, occurring often in extensive beds and irregular masses, interstratified in rocks of all ages, in such a manner as to form a true rock mass. Associated with gypsum, sylvite, anhydrite, calcite, clay, sand, etc. Occurs also dissolved in the waters of salt springs, salt seas and the ocean. The deposits of salt have been formed by the gradual evaporation and ultimate drying up of enclosed bodies of salt water. The salt beds formed in this way have subsequently been covered by other sedimentary deposits and gradually buried beneath the rock strata formed from them. Halite, or common salt, is the best known and most abundant of the native chlorides. It is a colorless, transparent mineral occurring in crystals, and in granular and compact masses. The mineral is plastic under pressure, and its plasticity increases with the temperature.

Identification and Diagnostics
In the closed tube halite fuses and often it decrepitates.
When heated before the blowpipe it fuses (at 776) and colors the flame yellow. The chlorine reaction is easily obtained by adding a small particle of the mineral to a microcosmic salt bead that has been saturated with copper oxide. This, when heated before the blowpipe, colors the flame a brilliant blue. The mineral easily dissolves in water, and its solution yields an abundant white precipitate with silver nitrate. Salty taste. Distinguished from sylvite (KC1) by its yellow flame color and by the latter having a somewhat more bitter taste.

Occurrence, Localities and Origins:
The principal mines of halite, or rock salt, are at Wieliczka, Poland; Hall, Tyrol; Stassfurt, Germany, where fine crystals are found; the Valley of Cardova, Spain; in Cheshire, England and in the Punjab region of India. At Petit Anse in Louisiana, in the vicinity of Syracuse, N. Y., and in the lower peninsula of Michigan thick beds of the salt are buried in the rocks far beneath the surface. Much of the salt is comparatively pure and needs only to be crushed to become usable. In most cases, however, it is contaminated with clay and other substances. In these cases it must be dissolved in water and recrystallized before it is sufficiently pure for commercial uses. The best known deposits are at Stassfurt where there is a great thickness of alternating layers of halite, sylvite (KC1), anhydrite, gypsum, kieserite (MgS04 -H2O) and' various double chlorides and sulfates of potassium and magnesium. Most of the salt produced in the United States is obtained directly from rock salt layers by mining or by a process of solution, in which water is forced down into the buried deposit and then to the surface as brine, which is later evaporated by solar or by artificial heat. In the district of Syracuse, N. Y., salt occurs in thick lenses inter-bedded with soft shales. In eastern Michigan and in Kansas salt is obtained from buried beds of rock salt, and in Louisiana from great dome-like plugs covered by sand, clay and gravel.

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Please note that the author, Chris Ralph, retains all copyrights to this entire document and it may not be reproduced, quoted or copied without permission.

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