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Sec. II, Ch. 12: The Carbonado Diamond

Sec. II, Ch. 12: The Carbonado Diamond Page of 366 Sec. II, Ch. 13: Value of Rough Diamonds Text size:minus plus Restore normal size   Mail page  Print this page
Carbonado.
145
to the surface, the débris formed by the action of the crown. Under favourable circumstances hard granite would be readily cut at the rate of 3 in. to 4 in. per minute.
The Diamond apparatus does its work entirely by friction. Its action is simply an abrading one, and effected neither by cutting nor percussion. It grinds or crushes the rocky stratum by its adamantine density. The difference between the relative hardness of the Car­bonate and ordinary rock is such, that several thousand feet might be bored with a crown properly set with good stones, before any serious wear would take place. The principal loss does not result from actual wear, but from the breakage which is caused when one of the stones be­comes loose in its setting, or from some accidental cleavage which occurs ; the fragments, unable to escape from be­neath the crown, invariably injure the other stones.
L
Sec. II, Ch. 12: The Carbonado Diamond Page of 366 Sec. II, Ch. 13: Value of Rough Diamonds
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