This state lias furnished nearly all the corundum of commerce for the United States, but the statistics of the mines and works have never been published. There has been much waste of effort in mining for the gem varieties, encouraged by occasional discoveries,... Report of the Bureau of Mines - Página 216por Ontario. Bureau of Mines - 1899Vista completa - Acerca de este libro
| Canadian Institute - 1898 - 334 páginas
...south-western counties of North Carolina, where corundum was first discovered in 1870. This state has furnished nearly all the corundum of commerce for the United States, but the statistics of the mines ;md works have never been published. There has been much waste of effort in mining for the gem varieties,... | |
| Ontario. Legislative Assembly - 1899 - 1074 páginas
...well as in gravel-beds. The principal deposits are found in association with magnesian rocks, chieHy peridotites. which occur as small lenticular masses...mining for the gem varieties, encouraged by occasional discoveiies, but chictly by the attractive colors in which the corundum is found. The whole process... | |
| Ontario. Department of Mines - 1899 - 282 páginas
...southwestern counties of North Carolina, whore corundum was first discovered in 1870. This state has furnished nearly all the corundum of commerce for...chiefly by the attractive colors in which the corundum ie found. The whole process of mining and milling has had to be learned by experience ; and the task... | |
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