It seems odd to me that prospectors would make a lot of money selling gold ore, or even smelting it to actual gold, since it takes a lot of gold ore to make gold.
The California Gold Rush did not involve ore until its last phase. The goal was to wash dirt and/or gravel to cause heavier gold dust and nuggets to separate from the rest of the debris. It could then be removed with tweezers or with mercury, forming an amalgam that could be cooked to drive off the mercury, leaving gold.
Realistic expectations was that a gold miner could retrieve several thousand dollars so he could return to "the states" to buy the farm of his dreams. Only a minority actually succeeded. These gold washers could not hope to become millionaires (unless they had unrealistic fantasies). As gold-yielding deposits (Largely in river and creek beds) were "worked out" by the mid 1850s, some sought underground ore bodies, and this called, ultimately, for a financial infrastructure to allow for underground mining and milling. The Empire Mine is a good example of a late-1850s (it started in 1850, but really took off at the end of the decade) effort in that direction, but by then, the Gold Rush was all but over - and it was basically ended for the common man.
This is largely based on a collection of letters from the Gold Rush, which I edited with a friend.
I do not know but a good Primary Source & fantastic read is Diary of a Forty Niner