(Written by Colonel J.C. Fremont in 1847 (and updated in 1852) about his explorations and observations of California during the Gold Rush.)
During a visit I made last spring, four such ovens were in operation, and yielded in the two days I was there 656 pounds of quicksilver, worth at Mazatlan $180 per pound. Mr. Walkinshaw, the gentleman now in charge of this mine, tells me that the vein is improving, and that he can afford to keep his people employed even in these extraordinary times. The mine is very valuable of itself, and will become the more so as mercury is extensively used in obtaining gold. It is not at present used in California for that purpose, but will be at some future time. When I was at this mine last spring, other parties were engaged in searching for veins, but none have been discovered worth following up, although the earth in that whole range of hills is highly discolored, indicating the presence of this ore. I send several beautiful specimens, properly labelled. The amount of quicksilver in Mr. Forbes' vats on the 15th of July was about 2,500 pounds.