Mineralogy: An Introduction to the Study of Minerals and Crystals

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McGraw-Hill book Company, Incorporated, 1920 - Crystallography - 561 pages
 

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Page 90 - The standard scale, which consists of 10 common minerals arranged in order of increasing hardness, is as follows: 1. Talc 2. Gypsum 3. Calcite 4. Fluorite 5. Apatite 6. Feldspar 7. Quartz 8. Topaz 9. Corundum 10. Diamond By using the above reference minerals, the hardness of an unknown mineral can be determined.
Page 90 - ... as follows: (1) talc; (2) gypsum; (3) calcite; (4) fluorite; (5) apatite; (6) orthoclase; (7) quartz; (8) topaz; (9) sapphire; and (10) diamond.
Page 99 - ... that the angle of reflection is equal to the angle of incidence, and the reflected and incident rays lie in the same plane.
Page 90 - The specific gravity of a solid is its weight compared with the weight of an equal volume of distilled water at the temperature of 39.2 F.
Page 117 - ... monochromatic light they are alternately light and dark. The distance between the optic axes or "eyes" gives some indication of the size of the angle of the optic axes. The closer together the "eyes" are, the smaller is the angle (Fig.
Page 117 - Figure 28, 90 position. In white light, the curves are colored, while in monochromatic light they are alternately light and dark. The distance between the optic axes or "eyes" gives some indication of the size of the angle between the optic axes, designated as 2 E.
Page xiii - A mineral may be defined as a substance occurring in nature with a characteristic chemical composition, and usually possessing a definite crystalline structure, which is sometimes expressed in external geometrical forms or outlines.
Page 88 - The terms perfect, imperfect, good, distinct, indistinct, and easy are used to indicate the manner and ease with which cleavage is obtained. Luster. — The luster of a mineral is the appearance of its surface in reflected light, and is an important aid in the determination of minerals.
Page 137 - ... river sapphire. Light-colored sapphire from Montana. RJ Abbreviation for Registered Jeweler, AGS roasting. Heating at a low red heat with a strongly oxidizing blowpipe flame, for the purpose of driving off sulphur, arsenic, etc. robold pearl. A trade term for a pearl which is not quite round. rock. Any mineral or aggregate of minerals comprising an important part of the earth's crust. Rock may consist of a single component, as a limestone, or of two or more minerals (Kraus and Hunt). Lapis lazuli...
Page 350 - Sublimed blue lead consists of lead sulphate 50 — 53 per cent, lead oxide 38 — 41 per cent, with small amounts of lead sulphide, lead sulphite, and zinc oxide. Minium is used as a red pigment. Various mixtures of "white lead" and zinc oxide are used as white pigments.

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