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416 PRECIOUS STONES IN THE UNITED STATES.
similar volcanic rock, containing a carbonaceous shale, was found in Elliott County, Kentucky, by Mr. J. S. Diller; and the possibility of diamonds being found there, was suggested by Professor Carvill Lewis, and led to a systematic search by Mr. Diller and the writer, under a mission from the United States Geological Survey. Diamonds were not found, and the shale was found to contain only l-35th as much carbon as the South African rock. Still there is a possibility, that the eruptive rock may have penetrated richer layers of the carboniferous and Devonian rocks elsewhere.
Of the corundum or sapphire gems, more than fifty have been found at the Jencks Mine, Franklin, North Carolina, where corundum mining was carried on some years ago, and has recently been resumed Jto supply mineral for a grinding or polishing substance. Fully one-half of these were really gems in every sense of the word. Some ruby-red ones were of a fair color. The blue sapphire and some fine violet-blue, light red, pink, and yellow sapphires, were also found. None of these gems had a higher value than a hundred dollars. An emerald-green sapphire (Oriental emerald), measuring 4 by 2 by ij inches, that would furnish from 80 to 100 carat weight of gems, the largest being about 20 carats in weight, is now in the cabinet of Mr. Clarence S. Bement, with the choicest crystals found at this mine. The gem is one of the rarest known. It will not be cut, however, since its owner prizes it much more highly in its natural state. This locality has also furnished some fair cabochon rubies, weighing over one carat. Vernon, New Jersey, has furnished some crystals of sapphire and ruby, which are brilliant though opaque, thus possessing little commercial value. The largest known crystal of sapphire came from the Jencks Mine about 1872. It weighed 312 pounds, and was both red and blue, ruby and sapphire, in color. It is now in the Shepard collection at Amherst College, and was considerably injured in the disastrous fire of 1882. Rubies and sapphires, always more or less opaque, have been found at many localities in North Carolina and Georgia.
The finest sapphires for gems, are collected by the miners from the sluice-boxes of the placer mines near Helena, Montana. The gems are usually light green, blue, red, and all the intermediate shades. One of these rough crystals is shown in Fig. 2 of the plate. Often they are blue, as viewed in one direction, and red when seen in another. Frequently all the colors would assume a red hue by artificial light. A very interesting piece of jewelry was recently made from these stones in the form of a crescent. At one end, as seen by daylight, the stones were red, shading to a bluish-red in the centre, and finally into blue at the other end ; but by artificial light the color of all turned red. A few small gems less than cne carat in weight, have come from the same place that were truly ruby red and sapphire blue. Of the latter color, perfect gems have been found here up to nine carats in weight. By artificial light these ar« intensely brilliant.
The colored plate shows (Fig. 3) the first sapphire ever found in its • original matrix. It consists of the stone from which a kernel of blue sapphire had dropped out. This kernel was then cut, and replaced in its original matrix. A white band running across the centre of both, shows conclusively that it belonged there. It was mined by Colonel C. W. Jencks, at Franklin, North Carolina. Near this place, brown crystals of sapphire have been found, in which, when they are cut en cahochon, so that the dome of the cut'stone is parallel with the perpendicular axis of the crystal, an asteria effect is produced, but not as fine as the Oriental.
Spinels of a smoky blue, velvet green, and dark tinted claret-color have been found in gems weighing about two carats each, near Hamburg, New Jersey. Some fine ones weighing about two carats each, were unearthed in San Luis Obispo, California. Twenty years ago, somewhere between Monroe and Southfield, Orange County, New York, a deposit was known only to two persons, now deceased. The locality was worked- secretly for some years by
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