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Show 594 WESTERN WILDS. partly over an original granite ridge was poured, at a very late geolog-ical era, an enormous flow of porphyry, or trachyte; that after the trachyte had become solid rock there were terrible convulsions which split and cracked it, and through the cracks gushed streams of obsidian, or vol-canic glass. All these ap-pear as they hardened into shape; so there is little wonder that the district was at first a great puzzle, seemingly destined to over-throw many old theories. Of course, too, there was great waste at first in work-ing this peculiar ore, but with experience the total cost per ton for mining and milling has been reduced to about seven dollars. This makes, it possible to work ten ounce ore at a profit, and as the supply of ore of that grade is practically in-exhaustible, it looks as if this magic district would be as long- lived as it was noted for sudden growth. But time and space fail me to detail each of the rich districts of Colorado. The following table, showing the increase in the population of the state by counties, will give the reader a very fair idea of the localities in which the richest mines have been developed, since the crowd invari-ably flocks to those places in which the rich metal is found: |
