Sec. I, Ch. 2: Where Precious Stones are Found

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	Where Precious Stones are Found.	7

	favourable to the blossoms of the inorganic world, than the dark skies of the north. But although modern researches have shewn that Precious Stones are not limited to any defined geographical area, their distribution is yet in a measure circumscribed, inasmuch as they are not met with in all mountain ranges, nor in all geological formations. The most valuable are found in such ranges as are composed of rocks considered to be among the most ancient in the world—in rocks composed of granite, gneiss, porphyry, mica-schist, and crystalline limestone. Sometimes they occur imbedded in the mass of the rock ; at other times, protruding, as it were, from the surface and jutting forth into free cavities, When they are thus found in the very rocks where they were originally formed they are said to be in their primitive bed. Many however, are found far from their primal home, in a derivative or secondary deposit, in diluvial or alluvial soils, in the gravels or sands of river-beds. This last mode of occurrence is perhaps the most frequent for the finer Precious Stones. Far removed from their native home by the force of heavy rains and rushing torrents, they have been loosened and carried onwards, rounded by friction against the débris with which they have been accompanied in their course. It is a strange fact that those stones which have been washed in the currents or deposited in river-beds, are generally found to be the finest. Possibly this may be explained by a process of natural selection which has weeded out the faulty stones, and left only those that, by their superior hardness, could survive the rough usage to which they have been subjected. It is their hardness and density that have not only preserved them from destruction, but have enabled many to retain traces of their original

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