California Gold
(Written by Colonel J.C. Fremont in 1847 (and updated in 1852) about his explorations and observations of California during the Gold Rush.)

I would recommend that a mint be established at some eligible point of the Bay of San Francisco; and that machinery, and all the necessary apparatus and workmen, be sent out by sea. These workmen must be bound by high wages, and even bonds, to secure their faithful services, else the whole plan may be frustrated by their going to the mines as soon as they arrive in California. If this course be not adopted, gold to the amount of many millions of dollars will pass yearly to other countries, to enrich their merchants and capitalists. Before leaving the subject of mines, I will mention that on my return from the Sacramento, I touched at New Almoder, the quicksilver mine of Mr. Alexander Forbes, Consul of Her Britannic Majesty at Tepic. This mine is in a spur of the mountains, 1000 feet above the level of the Bay of San Francisco, and is distant in a southern direction from the Puebla de San Jose about twelve miles. The ore (cinnabar) occurs in a large vein dipping at a strong angle to the horizon. Mexican miners are employed in working it, by driving shafts and galleries about six feet by seven, following the vein.