Our Black Rock Placer Claim in located a few miles north of the old mining town, La Porte. This mining district is located in southwestern Plumas County, which is about 25 miles south of Quincy and about 50 miles north of Oroville. Historically, the La Porte Mining District was the greatest of the placer mining districts in the state of California. The streams were placer-mined early in the gold rush and were reported to have had very rich yields. Reportedly, during the time of 1855 to 1871 the output of gold from this area was a staggering $60 million. Some mining activity still continues today, but has slowed since the 1930s.
Geology- At La Porte the channel is 500 to 1500 feet wide and as much as 500 feet thick. The lower gravels are quartz-rich and up to 80 feet thick. Most of the gold was recovered from near bedrock. The gravels are capped by thick beds of sand and pipe clay. During the heyday of mining in the district, these lower gravels yielded from 1/10 to as much as one ounce of gold per cubic yard. There are some narrow gold-quartz veins in the district.
Work Cited: “Gold Districts of California” Edition 193. William B. Clark. 1998