has
been reached. The mountain ridges above the streams are described as
quartzose chloritic talcschist, and the sands lie on a bed of dolomite.
A
few microscopic diamonds have been found in Russian Lapland in the
valley of the Pasvig river. Gneiss is the bed-rock, and the associate
minerals are with one or two variations the same as in India and Brazil.
A
few diamonds have been found in the Sierra Madre, southwest of Acapulco
in Mexico, and one was found in sand with Pyropes at Dlascekowitz, in
Bohemia. A report of one discovered in Ireland was not authenticated.
There
is a Jesuit tradition that diamonds have been found on Jesuit lands in
the district of Tena, 30 miles from Bogota, Colombia, but several
years' search has failed to discover any.
Strata
of clay said to be similar to kimberlite exists in the State of
Trujillo, Venezuela, and a concession was obtained from the government
some years ago to work them for diamonds, but none were found.
A
few diamonds have been found at various times in the United States, but
until the discovery of what is thought to be a diamond chimney like
those of Africa, in Pike County, Arkansas, in 1906, the fields gave no
promise of others, sufficient to induce prospecting for more. Single
stones have been picked up at long intervals, chiefly along the
eastern base of the Appalachians, in Virginia, North and South
Carolina, Georgia, and Alabama. Most of them have been found,
associated with gold, in the Carolinas, though the largest, weighing
23-3/4 carats, was found by a laborer while working in an excavation in
a street of Manchester, Virginia, in 1855. This crystal was an
octahedron with rounded
