The Arizona Geological Survey has just released another paper about Arizona mining: The History of the Silver Bell Mining District (AZGS Contributed Report CR-17-A). The paper is authored by geologist and mining historian David Briggs who has written about many of Arizona’s mining districts. The paper is available for free download (link).
The Silver Bell mine and the town of Silverbell are located about 36 miles northwest of Tucson, Arizona. It has produced copper and other metals since 1873 and silver since 1865. Prior to that, the Tohono O’odham Indians and/or their predecessors mined turquoise, hematite and clay, which were used for pottery, paint and decorative purposes.
The Silver Bell mine has had a colorful and sometimes contentious history. Briggs writes that “Over the past 150 years, the Silver Bell mining district evolved from a collection of small, intermittent, poorly financed and managed underground mining operations that struggled to make a profit from high-grade ores; to a small but profitable producer, deploying innovative mining practices and advancements in technology to successfully develop the district’s large, low-grade copper resource.”
Besides a detailed history of owners and operations, the report contains many historic photographs of the mining operations and the town.
Briggs: “Over past 130 years, the Silver Bell mining district yielded approximately 2.27 billion pounds of copper, 6.6 million pounds of molybdenum, 3.7 million pounds of lead, 40.8 million pounds of zinc, 2,100 ounces of gold, and 5.95 million ounces of silver.”
The mine now produces copper by leaching and electro-winning. Remaining reserves are reported to be 214.4 million tons, averaging 0.283% copper. Local geologists suspect there are more copper resources east and west of the active mining area, but that ground is effectively off-limits because it lies within Ironwood Forest National Monument. The monument was imposed over valid pre-existing mining claims. IFNM is one being reconsidered by the Trump administration.
Other papers by David Briggs: