BTW more important to the union than Sierra Nevada gold were the mercury deposits in New Almaden 50 miles south of the city. The mineral was used in percussion caps and the south bay had one of the largest deposit in the world at the time.
I read once that this was the main reason Lincoln pressed so hard to have California join the union.
I mountain biked there, and the area still has signs posted warning not to eat the fish in the nearby lake.
The area has a really cool story; an entire town in Wales moved, almost en masse, to the area to work the mines.