Wednesday, August 29, 2012

Arizona's other mineral resources - manganese

I gave the opening talk at the Arizona Mining Association's annual board meeting and strategic retreat the other day, describing some of the exploration underway around the state for minerals other than copper, gold, and silver.  One of the most interesting targets is for manganese, a metal critical to the manufacture of steel.     Arizona produced almost a quarter billion pounds of manganese but not only is none produced today, there is no manganese produced anywhere in the US.  All manganese used in the US for steel production (and certain aluminum products) is imported.   The National Academy of Sciences ranked manganese as a strategic and critical mineral highly vulnerable to supply disruption.  The global demand for manganese increased in the past half decade, in part driven by rapid development in China and other emerging economies.

AZGS Chief Geologist Jon Spencer is currently mapping the Artillery Mountains Manganese District in western Arizona, the largest historical manganese area in the state.  Jon makes the case that the western Arizona manganese province is probably the only significant manganese resource in the United States and the Artillery manganese district contains the largest known manganese deposit in the province.  [Right, manganese mining districts in western Arizona. Credit, AZGS]

Jon says most manganese concentrations are bedded and are thought to be detrital, with manganese washing in with the Miocene (8-12 Ma) sand and silt. Some deposits are vein and fracture filling, but most are bedded. Some disseminated ore may have been introduced by low-temperature hydrothermal fluids that also deposited very minor barite and calcite.

A US government manganese stockpile sits next to the railroad tracks outside of Wenden in La Paz County, western Arizona. This stockpile was the result of the US government manganese buying program in the early 1950s, and is the repository of most or all of the manganese produced from the surrounding manganese districts, including the Artillery manganese mining district. Congress recently authorized sale of the stockpile.

There is an exploration program underway in the area by American Manganese Co.

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