An Elementary Treatise on Mineralogy: Comprising an Introduction to the Science

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W. D. Ticknor & Company, 1844 - 662 sider
 

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Side xxv - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees ; each degree into 60 equal parts, called minutes ; and each minute into 60 equal parts, called seconds.
Side 98 - adamant harder than flint," '< that by Shamir is intended some variety of Corundum, a mineral inferior only to the diamond in hardness. Of this mineral there are two principal groups ; one is crystalline, the other granular ; to the crystalline varieties belong the indigo-blue sapphire, the red oriental ruby, the yellow oriental topaz, the green oriental emerald, the violet oriental amethyst, the brown adamantine spar.
Side xxvi - These planes are said to be similar, when their corresponding edges are proportional, and their corresponding angles equal. Edges are similar, when they are produced by the meeting of planes respectively similar at equal angles; and angles are similar when they are equal, and are contained within edges respectively similar. Sometimes it happens that the crystal is bounded in all directions by perfectly equal and similar faces, as is seen in the cube, octohedron, and rhombohedron. Such forms are distinguished...
Side 8 - ... iron and manganese which it contains : it becomes white and opalescent by long exposure to heat. The best amethysts are brought from Cambay, in India, from Siberia, Ceylon, and Persia, where they are found both lining the cavities of geodes and in rolled masses ; of inferior transparency and hue, they occur in Sweden, the Hartz, Bohemia, Transylvania ; in agate balls at Oberstein, in Germany ; in large crystalline groups near Cork ; and in several parts of the United States.
Side 194 - ... portion of the contents of the old species of feldspar, in which, from its wide distribution and known applications, mankind are more generally interested. Its crystals and crystalline masses yield to cleavage parallel to the planes of a doubly oblique prism, which presents, by the reflective goniometer, in one direction, four angles of 90° ; in another, four, alternately of 59° 25...
Side lxxxii - The same number of atoms combined in the same way produce the same crystalline form, and the same crystalline form is independent of the chemical nature of the atoms, and is determined only by their number and relative position.
Side 42 - It occurs in aggregated crystalline masses, deeply striated, or in separate crystals, of several varieties of form, and sometimes in that of its primary crystal, an oblique rhombic prism, of which the inclination of the terminal plane is from one acute angle to the other. It is white, sometimes with a tinge of red, and is translucent, and bard enough to scratch glass.
Side 151 - Shaw, use steatite in their baths instead of soap; and it is confidently asserted that the inhabitants of New Caledonia either eat it alone, or mingle it with their food. Humboldt says, that the...
Side lx - Haiiy have shed over mineralogy a purely philosophical luster which indeed has been one of the chief causes of raising the study to the rank of a science ; this he has done by showing the consonance of the laws of crystallization with rigid calculation: he has proved that in crystallization there is a natural geometry.
Side 635 - Botryoidal. From the Greek, (botruodes) signifying, hung with clusters of grapes or berries. So a mineral presenting an aggregation of large sections of numerous small globes, is termed botryoidal ; but when the globes are larger, and the portions are less, and separate, the appearance is expressed by the term mamiliated.

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