Gold Mining in Pennsylvania
Lead-silver mines with some gold were worked in Pennsylvania, specifically in Montgomery and Chester counties. A mine in Chester County was opened in 1850, and other mines were developed later. Gold was found in the clay underneath the city of Philadelphia in 1861. The clay bed was an extent of three square miles and average probably 15 feet in thickness. The gold content based on samples reported 1 part gold in 1,224,000, 1 cubic feet weighs nearly 120 pounds, and as the assays gave 0.7 gr of gold per cubic feet.
The lead veins of Montgomery and Chester counties yielded some silver, although they were worked for lead and copper chiefly. There were ten to twelve veins lying close to the junction of the New Red sandstone and gneiss, some of which traversed gneiss while others were in red shale, the latter being characterized by yielding copper ores. The main gangue was quartz and heavy spar. The following mines were worked for lead and silver: Chester County, Wheatley, Brookdale and Charlestown.