I found a couple of letters in the Rocky Mountain News that describe the mining at Cache Creek or "Cash Creek" in 1862. The writer claims it is one of the best mining regions in the country. He says he saw a nugget taken from the area that weighs "27 dollars." And "the gold is very coarse, the mines easily worked and pay certain. You can depend on the truth of these statements; they are not exaggerated."
What is so great about finding these letters (besides the great descriptions) is that the writer became a partner in a mining company with Wilburn Christison and others a couple of years later.