Boron, California Operations U.S. Borax
Mining and Refining. We produce approximately 1 million tons of refined borate ore every year from our Boron mine. It produces about a third of the world's supply of refined borate products. The mine measures 1.74 miles (2.8 km) wide, 1.99 miles (3.2 km) long, and is up to 755 feet (230 m) deep.