Halite Halite,
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.
Salt domes are vertical diapirs or pipe-like masses of salt that have
been essentially "squeezed up" from underlying salt beds by mobilization
due to the weight of overlying rock. Salt domes contain anhydrite,
gypsum, and native sulfur, in addition to halite and sylvite. They are
common along the Gulf coasts of Texas and Louisiana and are often
associated with petroleum deposits. Germany, Spain, the Netherlands,
Romania and Iran also have salt domes. Salt glaciers exist in arid Iran
where the salt has broken through the surface at high elevation and
flows downhill. In all of these cases, halite is said to be behaving in
the manner of a rheid.
Unusual, purple, fibrous vein filling halite is found in France and a
few other localities. Halite crystals termed hopper crystals appear to
be "skeletons" of the typical cubes, with the edges present and
stairstep depressions on, or rather in, each crystal face. In a rapidly
crystallizing environment, the edges of the cubes simply grow faster
than the centers. Halite crystals form very quickly in some rapidly
evaporating lakes resulting in modern artifacts with a coating or
encrustation of halite crystals.[4] Halite flowers are rare stalactites
of curling fibers of halite that are found in certain arid caves of
Australia's Nullarbor Plain. Halite stalactites and encrustations are
also reported in the Quincy native copper mine of Hancock, Michigan..
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