File:Transactions (1871) (14765663714).jpg

Identifier: transactionsmining35amer (find matches)
Title: Transactions
Year: 1871 (1870s)
Authors: American Institute of Mining, Metallurgical, and Petroleum Engineers
Subjects: Mineral industries
Publisher: New York (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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ns to therule. There is a difference in the luster, shape or crystallineform of the diamonds from the various mines that gives eachmine some distinctive characteristic. In one mine nearly allof the crystals are sharp-edged octahedrons, while in another,dodecahedrons with rounded faces predominate. One mightgive no end of peculiarities of the diamonds from the variousmines; but it will suffice for the purposes of this paper to statethe fact that such distinctive characteristics do occur. From this observation it may be concluded that the diamondsin the mines of the Kimberley district, which occupies a smallarea (see Fig. 1), did not have a common origin. The diamond is the most impenetrable of all known sub-stances, and will scratch any other stone, or the hardest steel.It is a very strong reflector of light, and refracts incident raysmore than any other substance except crocoite.1 1 Table of Indices of Refraction, in Dufrenoys Traite de Mineralogic. TI1K (JKNKSIS OF Til K KIAMnND. 441
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Fig. 1.—Diamond Mines in the Kimberley District, South Africa. 442 Till-: GENESIS OF THE DIAMOND. While crocoite is the only mineral that exceeds the disper-sive power of diamond to dissolve white Light into rainbow-tints; in its powers of reflection, retraction and dispersion takentogether, the diamond is unmatched.2 It is highly phosphor-escent, and even the blackest diamond is transparent to theX-ray. It is insoluble in all acids, and can easily be burnedand converted into carbon dioxide. However, it is noteworthythat the diamond is a non-conductor of electricity, while graph-ite and amorphous carbon, substances so closely allied to it inchemical composition, are good electrical conductors. By theapplication of friction, the diamond can be positively electrified,but it very soon loses its electricity. The diamond is easilycleaved in planes parallel to the octahedral faces. Pieces maybe easily broken from the facets of a cut stone by striking itwith a hard substance. So much, it m

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