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Sulfur Mineral Facts:

Chemical Formula: S  - It is native sulfur.

Colors: Bright yellow.
Bright yellow when pure, ranging to greenish, gray or brownish when impure. Bright yellow streak streak.

Hardness: 1.5 to 2.5

Density: 2.07

Cleavage: Imperfect, parallel to the prism (110) and tothe pyramid (111).

Crystallography: Orthorhombic
Pyramidal in habit Often with two pyramids, brachydome and base in combination.

Luster:. Resinous luster. Transparent to translucent.

Optics: (Refractive Index): = a= 1.9579, b= 2.337, y= 2.2452

Composition, Structure and Associated Minerals:
Sulfur is known in at least six different forms, four of which are crystalline. The two best known forms crystallize respectively in the orthorhombic (orthorhombic bipyramidal class) and the monoclinic (prismatic class) systems.  Sulfur is used for the manufacture of sulfuric acid, in making matches, gunpowder, fireworks, and insecticides, for vulcanising india-rubber and in bleaching processes involving the use of sulfur dioxide. Sulfur is an imperfect conductor of heat. When a fragment is held in the hand close to the ear it will be heard to crack. This is due to the expansion of the surface layers because of the heat from the hand, while the interior, on account of the slow heat conductivity, is unaffected. Crystals of sulfur should, therefore, be handled with care.

Recognized by its yellow color and the ease with which it burns. There are few minerals that are apt to be mistaken for sulfur. From all of them it may be distinguished by its brittleness and by the fact that it melts readily and burns with a nonluminous blue flame. At a temperature of 114 sulfur melts, and at 270 it ignites, burning with a blue flame and evolving fumes of SO₂. It is insoluble in water and acids, but is soluble in oil of turpentine, carbon bisulfide and chloroform.

Occurrence, Localities and Origins:
Sulfur occurs most abundantly around hot springs in regions of active or extinct volcanoes in connection with volcanoes, as a result of fumerole action. It is also found in beds associated with limestone and gypsum. In volcanic regions it is produced by reactions between the gases emitted from the volcanoes, or by the reactions of these with the oxygen of the air. The deposits in gypsum beds may result from reduction of the gypsum by organic matter. Sulfur is formed also as a decomposition product of sulfides.

Found in large deposits and in fine crystals near Girgenti,Sicily, associated with celestite, gypsum, calcite, aragonite, etc. Also found as fine crystals in conjunction with cinnabar and opal sinter at Steamboat Hot Springs near Reno, Nevada. Found in many areas in connection with the volcanoes of Mexico, Hawaii, Japan, Iceland, etc. In the United States it is found at the geysers of the Napa Valley, Sonoma County, and at Clear Lake, Lake County, California; at Cove Creek, Millard County, Utah; at the mines of the Utah Sulfur Company in Beaver County, in the same State; at Thermopolis, Wyoming, and at various hot springs in Nevada. The mineral occurs also abundantly in the Yellowstone National Park, but cannot be placed on the market because of high transportation charges. Massive forms are extracted through wells in Calsasieu Parish, Louisiana, and in Wyoming and Utah.

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Sulfur Crystals, Nevada

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