An Aboriginal Salt Mine at Camp Verde, Arizona. Anthropological Papers of the Museum of Natural History. Volume XXX, Part III. New York City, 1928. Museum Notes. Vol. 7, No. 10 April 1935.

San Manuel Mine was once the world’s largest underground copper mining operation in size of ore body, production capacity and infrastructure.

We mix anti-skid and salt together," said Himmelberger. "The temperature always plays a part in salt. I think 25 to 23 degrees it's a chemical reaction, so the colder it is the less salt breaks down." ...