STIBNITE MINERAL FACTS Nevada Turquoise gem stones
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Stibnite Mineral Facts:

Chemical Formula: Sb2S3  - 71.4 % Antimony by weight

Colors: Mineral and streak are lead-gray.
In very thin splinters it is translucent in red or yellow tints.

Hardness: 2.0

Density: 4.55

Cleavage: One cleavage that is very perfect parallel (010), leaving striated surfaces.

Crystallography: Orthorhombic
Slender prismatic habit, prism zone vertically striated. Crystals often steeply terminated, and often in radiating groups. Crystals sometimes curved or bent. Crystals of stibnite are often very complicated, and rendered that way by the great number of their terminal planes.
Many of the crystals of this mineral, more particularly those with an acicular habit, are curved, bent or twisted. Nearly all, whether curved or straight, are  longitudinally striated.

Luster:. Metallic luster, slightly transparent on very thin sections.

Optics: (Refractive Index): a = 4.303; y = 3.194

Composition, Structure and Associated Minerals:
Stibnite is the commonest and the most important ore of antimony. As found, however, it usually contains small quantities of iron and often traces of silver and gold. Surfaces that are exposed to the air are often coated with a black or an iridescent tarnish.  It is a nonconductor of electricity.

Identification and Diagnostics
Stibnite is characterized by its bladed structure, perfect cleavage in one direction, its lead-gray color and soft black streak. It fuses very easily, thin splinters being melted even in the flame of a candle. When heated on charcoal the mineral yields antimony and sulfurous fumes, the former of which coat the charcoal white in the vicinity of the assay. Stibnite may easily be distinguished from all minerals but the other sulfides by the test for sulfur. From the other sulfides it is distinguished by its cleavage and the fumes it yields when heated on charcoal. Its closest resemblance is with galena, which, however, differs from it in being less fusible and in yielding a lead globule when fused with sodium carbonate on charcoal. Moreover, galena possesses a cubic cleavage.

Occurrence, Localities and Origins:
Stibnite is deposited by alkaline waters in connection usually with quartz. Found as crystals in quartz veins cutting crystalline rocks or beds in granite and gneiss. Associated with other antimony minerals, as the products of its decomposition, and with sphalerite, galena, cinnabar, barite and sometimes gold. Found in various mining districts in Saxony, and Bohemia, Mexico, New South Wales, China, etc. Occurs in magnificent crystals in Province of lyo, Island of Shikoku, Japan. Found in quantity only sparingly in the United States, the chief deposits being in California, Nevada and Idaho. The mineral occurs also in York Co., New Brunswick, in Rawdon township, Nova Scotia, at many points in the eastern United States, in Sevier Co., Arkansas, in Garfield Co., Utah, and at many of the mining districts in the Rocky Mountain States.

In Arkansas stibnite is in quartz veins following the bedding planes of shales and sandstones. With it are found many lead, zinc and iron compounds and small quantities of rarer substances. In Utah the mineral occurs in veins unmixed with other minerals, except its own oxidation products. The veins follow the bedding of sandstones and conglomerates. Here, as in Arkansas, the stibnite is believed to have been deposited by magmatic waters.

Antimony is chiefly valuable as an alloy with other metals. With tin and lead it forms type metal. The principal alloys with tin are britannia metal and pewter. With lead, tin and copper it constitutes babbit metal, a hard alloy used in the construction of locomotive and car journals, and with other substances it enters into the composition of other alloys used for a variety of purposes, including bullets and wheel weights.

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Stibnite Crystals

Stibnite Crystals


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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