Occurs in crystals or compact masses; hardness, 4.5; specific gravity, 2.4; colorless to white; luster vitreous; translucent on thin edges.
The crystals when they occur, are monoclinic; but usually colemanite is a bedded deposit, which has resulted from the drying up of a saline lake. It was first found in Death Valley, Cal., in 1882, then near Daggett, Cal., and since then in several similar locations in Nevada and Oregon. The deposits are of all grades of purity, the colemanite being mixed with varying quantities of mud. Today this mineral is the chief source of borax, which is used in medicines, cosmetics, colored glazes, enamel, and as a preservative.
[Borax]
NaB₄O₇ + 10H₂O
Occurs in crystals or in powdery incrustations; hardness, 2; specific gravity, 1.7; colorless to white; luster vitreous; translucent on thin edges.
The crystals are tiny and monoclinic, this mineral being usually obtained by the evaporation of the saline waters of such lakes as Clear and Borax Lakes in southern California, or from the muds of salt marshes, like Searles Borax Marsh in California. Originally most of our borax came from a large saline lake in Tibet, but now most of it is obtained from colemanite. Borax is soluble in water, giving it a sweetish taste.
[Sulphur]
S
[Pl. 51]
Occurs in crystals, incrustations or compact masses; hardness, 2; specific gravity, 2; color yellow; streak yellow; luster resinous; translucent on thin edges.
Aside from the numerous compounds, such as the sulphides of the metals like pyrite, galena, sphalerite, etc., and the sulphates, like gypsum, barite, anglesite, etc., sulphur occurs in its elemental form in Nature. In this case it may be in crystals, which are orthorhombic and usually occur as octahedrons, with the upper and lower ends truncated, either by a basal plane, or by a lower octahedron, or by both. Incrustations and compact masses are, however, much the commoner mode of occurrence. The incrustations are found mostly about volcanic regions, where the sulphur has risen from the molten lavas as a sublimate, and on cooling has been deposited in crevices or on the adjacent surfaces. Irregular masses of sulphur are often found where sulphide minerals, like pyrite or galena have been decomposed in such a way as to leave the sulphur behind. The extensive beds of sulphur are usually associated with gypsum, and are thought to be the result of water, containing bituminous matter, so acting on gypsum as to remove the calcium and oxygen as lime, and leave the sulphur. Finally many waters carry sulphates in solution, from which the sulphur may be precipitated by certain sulphur bacteria, making thus incrustations on the bottom of ponds or lakes.
Sulphur is used for making matches, gunpowder, fireworks, insecticides, in medicine, vulcanizing rubber, etc. It is widely distributed, however, most of the present world’s production is from deposits associated with the “salt domes” of Texas and Louisiana. A “caprock” of gypsum and anhydrite overlies many of these which often contains elemental sulphur. Wells are drilled into this, and the sulphur is melted by the introduction of hot steam. This melted sulphur is then pumped to the surface and run into molds.
Some of the best known localities are Sulphurdale, Utah, Cody and Thermopolis, Wyo., Santa Barbara Co., Cal., Humboldt Co., Nev., and about the hot springs of the Yellowstone Park.