a
number of points, and at present, according to Henry G. Hanks, the
State Mineralogist, five counties, Amador, Butte, El Dorado, Nevada,
and Trinity, are known to have yielded them. Other localities and
larger numbers are yet, in his judgment, to be discovered. The
hydraulic mining is in some respects a wasteful and unfortunate
process, as the force of the current sweeps away the greater part of
any material that does not amalgamate with the mercury; and thus many
valuable substances are probably lost, such as iridosmine, platinum,
and diamonds. Moreover, whatever diamonds occur in the hard cement are
crushed into fragments by the stamps, and such fragments and particles
are not infrequent in the tailings and sluices. The following is a
brief summary of the principal diamond discoveries in California up to
the present time, arranged by localities. At Indian Gulch, near
Fiddletown, and Jackass Gulch, near Volcano, Amador County, numerous
diamonds have been found. In 1867, the younger Silliman of Yale College
exhibited several specimens before the California Academy of Sciences:1
one of these, a little over 1 carat in weight (3*6 grains) was from
near Fiddletown; and four others from the same region were at that time
known. These stones occurred in a compact volcanic ash or tufa, forming
a gray "cement-gravel." At Volcano the rock is similar, and some sixty
or seventy diamonds have been reported thus far. This is one of the
places where the cement-rock is worked by stamping, and the tailings
show pulverized diamonds. The crushed gravel pays well in gold ; and it
has not been thought desirable to change the present method and break
up the rock in other ways more costly and troublesome, in order to save
the diamonds that it may contain. In August, 1887, Mr. Hanks exhibited
before the San Francisco Microscopical Society, a beautiful stone of
1.57 carat weight (4*97 grains), found at Volcano in 1882, and
belonging to J. Z. Davis, a member of the society. It is a modified
octahedron, about 3/10 inch in diameter, transparent and nearly
colorless, though slightly flawed. The curvature of the faces gives the
crystal a subspherical form, but the edges of the pyramids are channels
instead of planes. Closer examination shows that the channeled
1 See Proc. Cal. Acad. Sci., Vol. 3, p. 354.
