it
will still be necessary to prove the presence of diamonds and in paying
quantities. Peridotite rocks are not uncommon, though few are known to
be diamond bearing.
California.—Frequent reports have appeared in the newspapers concerning the prospecting for diamonds near Oroville by Mr.
M. J. Cooney. It appears that washing machinery and more land are to be
purchased and extensive prospecting is to be carried on. Besides the
occurrence of a rock claimed to be identical in appearance with the
kimberlite of South Africa, reports state that diamonds have been found
associated with that rock. Authentic finds of diamonds in this section
of Butte County are recorded,0 especially at Cherokee above
Oroville. These diamonds have come from alluvial deposits, however, and
were generally found in washing for gold. Up to the present time no
authenticated discovery of diamond in its original matrix in California
is recorded. During the early part of 1907, specimens of serpentinized
rock called "kimberlite" from the sup-
posed
diamond pipe were kindly sent to the Survey by Mr. Cooney. These
specimens were discussed in this report for 1906. Upon careful
examination and comparison with typical kimberlite from South Africa,
it became evident that the Oroville rock was quite different from true
kimberlite.
Kentucky.—Newspaper
reports have appeared telling of the discovery of diamonds in Kentucky
during 1907, though no authenticated finds are recorded.
According
to the report of Mr. H. A. Millar, secretary of the Kentucky Diamond
Mining and Developing Company, the complete diamond washing plant
installed by that company on Creech's Creek in Elliott County was
operated during the latter part of the summer and in the early fall.
Overburden was removed from three portions of the kimberlite rock
outcrop, and some of the yellow ground was washed. Delays were caused
by the breaking of the gearing, and operations were finally closed for
the winter on the 22d of October, when the water supply for washing was
exhausted. Though a total of 2,825 loads of 18 cubic feet were washed
without finding diamonds, operations were to be resumed in the spring
of 1908.
SOUTH AFRICA.
Griqualand West.—According to the nineteenth annual report of the De Beers Consolidated Mines,6
the number of loads of "blue" raised and washed and the quantity and
value of diamonds obtained again showed large increases. The total
production of blue ground at all the mines— De Beers, Kimberly,
Wesselton, Bultfontein, and Dutoitspan—was 9,010,686 loads, as against
8,144,979 loads in 1906, and the total quantity washed was 6,626,291
loads, as against 5,625,592 loads in 1906. This leaves a remainder of
9,391,603 loads on the floors, as against 6,769,126 in 1906, an
increase of 2,622,477 loads. The number of carats of diamonds won from
all the mines and from the tailings and debris was 2,619,872, as
against 2,213,991 carats in 1906. The increase in the number of
diamonds won came from the Wesselton, Bultfontein, and Dutoitspan
mines, and from the increased quantity of tailings washed. The average
yield per
a Turner, H. W., Diamonds In California: Am. Geol., vol. 23,1899, pp. 182-191.
b Nineteenth Ann. Eept. De Beers Consolidated Mines for year ending June 30,1907.
