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Ch. 2: Precious Gem stones in 1893

Ch. 2: Precious Gem stones in 1893 Page of 36 Text size:minus plus Restore normal size   Mail page  Print this page
702
MINERAL RESOURCES.
corundum in the form of fine gems. It having been suggested that this material would cut and polish a diamond, an experiment was made on a new wheel in the mining building at the World's Columbian Exposition. After several trials it was found that the carborundum used would not scratch or polish the diamond, but on the other hana it was easily scratched by diamond cleavages and crystal faces.
This experiment is only mentioned as it precludes any possibility of the material which has been found in the Canyon Diablo meteorite being any compound of carbon and silicon, such as the new interesting and valuable abrasive material just mentioned. But it establishes the fact that we have here an artificial substance that exceeds all natural sab-stances except the diamond in hardness, i. e., being harder than 9, but still far distant from 10.
Ch. 2: Precious Gem stones in 1893 Page of 36
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US Geol. Surv. 1893. Gemstones, Metals.
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