On the San Jacinto estate, which is owned by an English syndicate, are
located the old Gavilan Mines, which years ago produced from quartz
veins considerable gold, the rock being first crushed in numerous
arrastras, the beds of which, to the number of fifty or more, are still
scattered all about the neighborhood of the mines. In later years, under
American management, the quartz was hauled to a stamp mill in the
Pinacate District. At the time the rancho became the property of the
English people nothing had been done in these mines for many years.
During the past two years the old workings have been investigated and a
local company organized at Riverside to operate them under lease. At the
time of my visit some workmen were industriously engaged in taking down
the gallows frame of the hoist and making preparations to vacate the
premises, and this in the face of the report that had gone abroad that a
good-sized vein of pay rock had been uncovered at the bottom of the mine
at the depth of 180 feet. I did not see the alleged ore shoot and could
get no satisfaction from the men at work other than vague hints that
there was dissension among the Board of Directors.
The veins of the Gavilan Mines are not large, but of good grade,
occurring in a granitoid rock. Black tourmaline in a feldspathic and
quartz gangue frequently accompanies the gold-bearing rock. The Mexicans
worked a large shoot down to the water-line, and judging from the size
and number of the dumps these old workings must have been of great
extent. The Riverside people had sunk a new shaft at the extreme south
end of the mine 180 feet in depth. The entire region is cut by large
feldspathic and granitic veins, which course in every direction. These
veins are doubtless intrusive dikes of the variety of granite called
pegmatite. White scales of muscovite occur sparingly, but tourmaline is
abundant.