In the 1920s, a mine producing high-quality silica sandstone was started by owner Marvin Greathouse on a hillside above the Somersville townsite. He sold the product to the Hazel-Atlas Glass Company which operated a plant in Oakland manufacturing glass containers. Hazel-Atlas eventually purchased the mine and operated it until about 1945. Another sandstone mine in the Nortonville area produced sand used by the Columbia Steel mill in Pittsburg, California for steel casting. The two companies recovered more than of sand between from the 1920s to the 1940s. The Hazel-Atlas mine is being restored and maintained by park staff and can be visited on guided tours which cover the area's mining history and geology.