Learn how silica becomes glass at Hazel-Atlas Mine

Hazle-Atlas Mine, East Bay Regional Park District

Learn how silica becomes glass at Hazel-Atlas Mine:

Perhaps you've been sipping summer iced tea out of a mason jar, or patting the side of a ketchup bottle at a barbecue. You might not know that glassware was once made locally, and you can still see where silica was once mined near Antioch at the Hazel-Atlas Mine on guided tours at the Black Diamond Mines Regional Preserve every Saturday and Sunday through November.

In an earlier era of mining, says Eddie Willis, a naturalist with the East Bay Regional Park District, the Black Diamond area represented the largest coal mining district in state of California. In the regional preserve at the foot of Mount Diablo are a dozen 19th century coal mines that have been sealed up for safety reasons and the five small ghost towns that once served the workers.

Abandoned at the turn of the 20th century, the area later opened to silica mining in the 1920s, when silica sandstone was sent to the Oakland factory of the Hazel-Atlas Glass Co. to make dishware and glass items. The Hazel-Atlas Co., which Willis says was once housed not far from the present-day Oakland Coliseum, would later purchase the mine and operate it until the end of World War II.

"The mine is set up to look like it did during 1930s operation," Willis says, explaining that the 90-minute guided tour starts with a slideshow and an overview of the park's history. After that, you put on hard hats and pick up flashlights for the trip into the shaft about 1,000 feet underground.

This Saturday at 10 a.m., a special naturalist-led program about silica mining, "Your Glass Starts Here," will trace the path of silica from the ground into modern manufactured products. (If you can't make it this weekend, the program takes place again Oct. 12.)

"For geology buffs, it's a great way to see geologic history. There are many different layers of earth that you can't see at surface, but which are visible in the mine," Willis says. "We also pass through a fault, a cut through the mine where earth has shifted, and along the way there are fossil imprints of ancient sea life.

"We try to tell the story of what took place here and why people came here to mine, as well as how the mines were used," he says.

Before or after the mine tour, there is plenty to see throughout the Black Diamond Mines Regional Preserve, including the remnants of a ghost town, an old cemetery with headstones for 19th century townspeople, and some 60 miles of hiking trails, both moderate and challenging. (Read more about the preserve at http://bit.ly/14t1g1v.)

Willis suggests that you wear closed-toed shoes if you go on the mine tour, and because the mine remains 58 degrees Fahrenheit regardless of the outside temperature, it's a good idea to dress in layers and bring a sweater or light jacket.