Coal Mining in the Bay Area

Did you know that the Bay Area once had the largest coal mine in California? And that the East Bay boasted one of the largest silica mines to produce glass bottles for Oakland companies like Heinz Ketchup from the 1920s-1940s?

Visiting the Black Diamond Mines in Antioch, I got to climb into one of the largest coal mines in California. Black Diamond Mines Regional Preserve run by the East Bay Regional Park District has a visitor center that stays the same temperature year-round. That's because it's in a former silica mine. The walls of sandstone are tinged with black from fires people used to light in the caves for parties back in the 1970s when the mine was abandoned.
These mines played an important part of the Bay Area's industrial development, as they produced the majority of the coal and glass that powered industry in Oakland in the first half of the 20th century.

What was interesting is that I couldn't find the early towns, where the miners lived, nor the railroad lines, which used to run through the hills. They've vanished, or been buried.
Outside the mines, there are scenic hills for hiking, and you can see the Carquinez Bridge in the delta from the tops of the hills. For more information about visiting the East Bay Regional Park, see the Black Diamond Mines Regional Preserve website.

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