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34
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GEMS AND PRECIOUS STONES IN THE
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tucky,
he found only '68 per cent, of carbon. The peridotite at the time of
its intrusion must have been forced up through a number of coal beds,
and at a greater depth it penetrated the Devonian black shale, which is
considerably richer in carbon than the shale now exposed at the
surface. It is quite possible, if the theory of the origin of diamonds
proposed by Professor Roscoe and independently advanced by Professor
Lewis be true, that a number of diamonds may have been formed in the
Kentucky peridotite; but the general paucity of carbon in the adjacent
rock is certainly discouraging to the prospector. The best time to
search for gems in that locality is immediately after a heavy rain,
when they are most likely to be exposed upon the surface. It is
proposed to continue the search economically, by furnishing to
responsible persons living in the vicinity a number of rough diamonds
mounted in rings, for comparison, that they may know what to look for
under the most favorable circumstances.
The
"Jewelers' Review" for June, 1888, gave an account of a diamond from
Russell County. It is described as a small octahedron, with curved
faces, lustrous and nearly white, though with a yellow tinge, and
weighing 7/16 of a carat. It was found in a gravelly field on the top
of a hill some 300 feet above Cabin Fork Creek. The country rock is
said to be composed of granite dykes, slates, and some floating rocks,
such as quartz, feldspar, magnetic iron ore, flint, garnet, etc.,
mingled in clayey hills. The rocks near Montpelier, Adair County, Ky.,
belong either to Keokuk or to the St. Louis group, probably to the
former. From the absence of any direct geological information
concerning the two counties, they have been referred to these groups by
Professor Proctor.
Various
reports of the discovery of diamonds in different parts of the country
are from time to time published by local papers; but they generally
prove to have been written without exact information as to the
character of the stone, or for speculative purposes. A few of these
reported diamonds will be referred to, of which only the following are
known to be genuine. Two diamonds have been on exhibition for several
years at the store of Frederick N. Herron, Indianapolis, and
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