Sphalerite, also called zinc blende or simply blende, is a lustrous mineral found in the central Mississippi region of the United States as well as in parts of Europe such as Spain and Germany. Flashier and more useful than your average chunk of stone, sphalerite owes its dazzling appearance and singular properties to the unique kind of rock it is.
Classification
Sphalerite is an igneous rock, meaning that it is formed by solidified magma (molten lava). It is classified as a sulfide, according to Amethyst Galleries' Mineral Gallery. Sulfides are forms of minerals which possess practical economic value, such as lead, copper and silver. Sphalerite's mineral name is zinc iron sulfide, since the rock itself is a major ore of the metal zinc.
Identification
In pure form, sphalerite is almost colorless, often making it difficult to identify, reports GeoKansas. However, many field specimens of sphalerite are impure and tend toward a brown, yellow, red or even black coloration. Sphalerite rock has a whitish streak present, one that is always lighter than the color of the surrounding rock material.
Features
Aside from its use as a zinc ore, sphalerite possesses aesthetic appeal to rock collectors and people who simply appreciate the sight of a lovely geological specimen. This is largely due to sphalerite's high luster, or its ability to refract light. The fire of certain sphalerite samples' mineral facets can even rival that of a diamond, reports Amethyst Galleries. The specific type of sphalerite's luster is scientifically termed adamantine, a shine with a metallic nature and a high light refraction index.
Significance
One especially significant property of sphalerite is its "cleavage," or the particular way the rock will break. Sphalerite contains six perfect directions of cleavage, enabling the rock to be broken into 12-sided blocks, states GeoKansas. Although the many facets of sphalerite can be a beautiful addition to a rock cabinet or collector's display case, they are fragile. The surface of sphalerite can easily be scratched by a knife or marred by contact with other hard objects, making the rock a delicate treasure with little application for fashioning potentially breathtaking sphalerite jewelry.
Fun Facts
Sphalerite is related to other sulfide rocks such as galena, pyrite, fluorite, quartz, calcite and magnetite. Sphalerite earned its name by the ease by which the rock can be mistaken for another sulfide--the name "sphalerite" comes from the Greek word "sphaleros," which means "treacherous," reports Mindat.org. Particularly dark varieties of sphalerite have often been mistaken by miners for the more economically valuable galena, or lead ore.
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