On January 22, 1865, Mark Twain went north from Jackass Hill, in nearby Tuolumne County, to Angel's Camp with Jim Gillis, who had a claim there. During their first week, heavy rains confined them to Tryon's Hotel; they spent the next three weeks prospecting with little success. Throughout this time -- especially during the rainy week -- Mark Twain exchanged yarns with locals, notably Ben Coon, and left with a notebook filled with story ideas. Chapter 61 of Roughing It briefly describes this period.
Named after Henry Angel, who discovered gold there in 1848, it began with placer mining and later, quartz mining. Twain was there "during a stagnant period". By the mid-1880's it was a premier gold-producing region. This lasted about 30 years, by which time most of the mines had shut down.
Twain had little success with mining but did record a number of "yarns" that he developed into stories and sketches.