Page 105 - califmining1924

STATISTICS OF ANNUAL PRODUCTION. 103

Total Production of Gem Materials in California.
Tlie value of the gem output in California annually since the begin-
ning of commercial production is as follows :

Year Value Year Value

1900 $20,500 1913 |13,740
1901 40,000 1914 -. . 3,970
1902 162,100 1915 . 3,565
1903 110,500 1916... ... 4,752
1904 136,000 1917 3,049
1905 -. -- 148,500 1918 .. 650
1906 497,090 1919 .. . .. . 5,425
1907 232,642 1920 36,056
1908 208,950 1921 10,954
1909 193,700 1922 . 1.312
1910 237.475 1923 13,220
1911-. - . . 51,824 1924 4,800
1912 -- 23,050
$2,163,824

GRAPHITE.
Bihliographij: State :\Iineralogist Reports XIII. XIV, XY, XVII.

Bulletins 67, 91. U. S. G. S., Mm. Res., 1914, Pt. 11.
(rrai)hite has been i)r()du('(Hl from time to time in the state, coming
principally from Sonoma and Los Angeh's counties. It is difficult for
lliese dei)osits. wiiicli must be concentrated, to compete with foreign
su[)plieH. wliich go on the market almost directly as they come from the
deposit. (Jraphite ores are concentrated with considerable difficulty,
and the electric process of manufacturing artitieial graphite from coal
has l)een perfected to such a degree that only deposits of natural
graphite of a superior quality can be exploited with any certainty of
success.
According to the U. S. Geological Survey, operators in this counti'A'
who are working disseminated flake deposits must depend on their No. 1
and 2 flake for their i)rofit. (Iraphite dust is merely a by-product and
is salable only at a low price. Improved methods of graphite milling
adopted promise to increase largely the production of flake of better
grade.
The principal value of graphite is on account of its infusibility and
resistance to the action of molten metals. It is also largely used in the
manufacture of electrical appliances, of 'lead' pencils, as a lubrieant,
as stove polish, paints, and in many otlier Avays. Amorphous graphite,
commonly carrying many imi)urities. l)rings a much lower price. For
some purposes, such as foundry facings, etc., the low-grade material is
satisfactory. Among the interesting uses for graphite is the prevention
of formation of scale in boilers. The action is a mechanical one.
being soft and slippery, the graphite prevents the particles of scale