Casket Quarry | Duluth Crushed Stone Co.
According to the 1943 book Mineral Resources of Minnesota, edited by William H. Emmons and Frank F. Grout, “the Duluth Crushed Stone Company quarried gabbro at Duluth for road stone, railroad ballast, concrete aggregate, rubble for retaining walls, and riprap (large fragments for piers, breakwaters, etc.).”