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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A mineral with composition ZnO (zinc oxide). It crystallizes in the hexagonal system with a wurtzite-type structure. Thus its principal axis is polar and different forms appear at top and bottom of crystals. Such crystals are rare and the mineral is usually massive. Cleavage is prismatic. Its hardness is 4 and its specific gravity 5.6. The mineral has a subadamantine luster and a deep-red to orange-yellow color. The color of the mineral is believed to result partly from the presence of manganese and partly from defects in the crystal structure. Zincite is rare except at the zinc deposits at Franklin and Sterling Hill, New Jersey. There, associated with franklinite and willemite, it is mined as a valuable ore of zinc.
Industry:Science
A mineral with the chemical composition CaSO<sub>4</sub>. Anhydrite occurs commonly in white and grayish granular masses, rarely in large, orthorhombic crystals (see <b>illus.</b>). Fracture is uneven and luster is pearly to vitreous. Hardness is 3–3.5 on Mohs scale and specific gravity is 2.98. It fuses readily to a white enamel. It is soluble in acids and slightly soluble in water. Anhydrite is an important rock-forming mineral and occurs in association with gypsum, limestone, dolomite, and salt beds. It is deposited directly by evaporation of seawater of high salinity at or above 108°F (42°C). Anhydrite can be produced artificially by dehydration of gypsum at about 390°F (200°C). Under natural conditions anhydrite hydrates slowly, but readily, to gypsum. It is not used as widely as gypsum. Anhydrite is of worldwide distribution. Large deposits occur in the Carlsbad district, Eddy County, New Mexico, and in salt-dome areas in Texas and Louisiana.
Industry:Science
A mineral with the chemical composition CuSO<sub>4</sub>· 5H<sub>2</sub>O. Chalcanthite commonly occurs in blue to greenish-blue triclinic crystals or in massive fibrous veins or stalactites (see <b>illus.</b>). Fracture is conchoidal and luster is vitreous. Hardness is 2.5 on Mohs scale and specific gravity is 2.28. It has a nauseating taste and is readily soluble in water. It dehydrates in dry air to a greenish-white powder.
Industry:Science
A mineral with the chemical composition MgSO<sub>4</sub>· 7H<sub>2</sub>O. Epsomite, or epsom salt, occurs in clear, needlelike, orthorhombic crystals. More commonly it is massive or fibrous, although crystals from salt lakes on Kruger Mountain near Orville, Washington, are reported to be several feet long. Fracture is conchoidal. Luster varies from vitreous to silky. Hardness is 2–2.5 on Mohs scale and specific gravity is 1.68. The mineral has a salty bitter taste and is soluble in water.
Industry:Science
A mineral with the chemical composition MnWO<sub>4</sub>. Huebnerite is the manganese member of the wolframite solid-solution series. It commonly contains small amounts of iron. It occurs in monoclinic, short, prismatic crystals. Fracture is uneven. Luster varies from adamantine to resinous (see <b>illus.</b>). Hardness is 4 on Mohs scale and specific gravity is 7.2. Huebnerite is transparent and yellowish to reddish-brown in color; streak is brown. It is fusible with difficulty.
Industry:Science
A mineral with the chemical composition PbCrO<sub>4</sub>. Crocoite occurs in yellow to orange or hyacinth red, monoclinic, prismatic crystals with adamantine to vitreous luster (see <b>illus.</b>); it is also massive granular. Fracture is conchoidal to uneven. Hardness is 2.5–3 on Mohs scale and specific gravity is 6.0. Streak, or color of the mineral powder, is orangish-yellow. It fuses easily.
Industry:Science
A mineral with the chemical composition PbSO<sub>4</sub>. Anglesite occurs in white or gray, orthorhombic, tabular or prismatic crystals or compact masses (see <b>illus.</b>). It is a common secondary mineral, usually formed by the oxidation of galena. Fracture is conchoidal and luster is adamantine. Hardness is 2.5–3 on Mohs scale and specific gravity is 6.38. Anglesite fuses readily in a candle flame. It is soluble with difficulty in nitric acid. The mineral does not occur in large enough quantity to be mined as an ore of lead, and is therefore of no particular commercial value. Fine exceptional crystals of anglesite have been found throughout the world. In the United States good crystals of anglesite have been found at the Wheatley Mine, Phoenixville, Chester County, Pennsylvania, and in the Coeur d'Alene district of Shoshone County, Idaho.
Industry:Science
A mineral with the chemical composition SrSO<sub>4</sub>. Celestite occurs commonly in colorless to sky-blue, orthorhombic, tabular crystals. Fracture is uneven and luster is vitreous. Hardness is 3–3.5 on Mohs scale and specific gravity is 3.97. It fuses readily to a white pearl. It is only slowly soluble in hot concentrated acids or alkali carbonate solutions. The strontium present in celestite imparts a characteristic crimson color to the flame.
Industry:Science
A mineral with the idealized composition ZrSiO<sub>4</sub>, one of the chief sources of the element zirconium. Trace amounts of uranium and of thorium are often present and the mineral may then be partly or entirely metamict. The name cyrtolite is applied to an altered type of zircon. Structurally, zircon is a nesosilicate, with isolated SiO<sub>4</sub> groups. It is isostructural with the thorium silicate thorite and the yttrium phosphate xenotime.
Industry:Science
A mineral, Ca<sub>2</sub>(Al,Fe<sup>3 +</sup>)(OH)<sub>2</sub>(Si<sub>3</sub>AlO<sub>10</sub>), with Al in parentheses in octahedral and Al in brackets in tetrahedral coordination by oxygens. The (Si<sub>3</sub>AlO<sub>10</sub>) tetrahedral sheet reflects its perfect platy cleavage. Owing to difficulty in securing suitable single crystals, the atomic arrangement of the mineral had not been known until recently. Prehnite crystallizes in the orthorhombic system, but various space groups have been assigned to it owing to Al-Si ordering, such as Pncm, P2cm, and monoclinic (pseudo-orthorhombic) P2/n.
Industry:Science
