Garrison (112.811W 46.523N) is a rail junction near Helena, Montana. The town was the center of a phosphate mining district. The phosphate came from the Phosphoria formation, which was up to 70 feet (21m) thick in this region, with the richest phosphate rock (up to 60% calcium triphosphate) coming from the Retort member, which was up to 5' (almost 2m) thick. Production ws relatively modest during the war years, at about 920 tons per year, but became much greater after 1945.

Rail connections



Fort William Henry Harrison


Montana Department of Environmental Quality (accessed 2013-5-31)

Van Royen and Bowles (1952)

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