Arizona may become a major producer of potash

What is potash?  No, it’s not residue from a joint. It’s a potassium salt used for fertilizer and in chemical processing.  A newly delineated deposit in the Holbrook Basin, about 30 miles east of Holbrook, holds a considerable resource estimated at  158 million metric tonnes of sylvinite, with about 16 million metric tonnes of K2O; and Inferred Resources of 560 million metric tonnes of sylvinite with just over 66 million metric tons of K2O.  Sylvinite is a mixture of potassium chloride and sodium chloride (not to be confused with sylvanite, a gold telluride mineral).


The deposit is hosted in evaporite deposits within Pennsylvanian to Permian aged siliciclastic sediments.  Potash occurs as discreet mineralized horizons within the uppermost halite beds of this evaporite sequence.  See section below.  Evaporite minerals are produced from the evaporation of mineral-laden water in an enclosed basin.  Just think of what would be left if the Great Salt Lake in Utah evaporated.  Similar events have occurred many times.  In fact, much of Phoenix is underlain by evaporite deposits.


A 100-page technical report prepared by North Rim Exploration for the property owner, American West Potash, is available here.

For some background on potash, the following is from the USGS mineral commodity summary for 2011:

Domestic Production and Use

In 2010, the production value of marketable potash, f.o.b. mine, was about $540 million. Potash was produced in Michigan, New Mexico, and Utah. Most of the production was from southeastern New Mexico, where two companies operated three mines. New Mexico sylvinite and langbeinite ores were beneficiated by flotation, dissolution-recrystallization, heavy-media separations, or combinations of these processes, and provided more than 75% of total U.S. producer sales. In Utah, which has three operations, one company extracted underground sylvinite ore by deep-well solution mining. Solar evaporation crystallized the sylvinite ore from the brine solution, and a flotation process separated the potassium chloride (muriate of potash or MOP) from byproduct sodium chloride. Two companies processed surface and subsurface brines by solar evaporation and flotation to produce MOP, potassium sulfate (sulfate of potash or SOP), and byproducts. In Michigan, one company used deep-well solution mining and mechanical evaporation for crystallization of MOP and byproduct sodium chloride.

The fertilizer industry used about 85% of U.S. potash sales, and the chemical industry used the remainder. More than 60% of the produced potash was MOP. Potassium magnesium sulfate (sulfate of potash-magnesia or SOPM) and SOP, which are required by certain crops and soils, also were produced.

World Resources

Estimated domestic potash resources total about 7 billion tons. Most of these lie at depths between 1,800 and 3,100 meters in a 3,110-square-kilometer area of Montana and North Dakota as an extension of the Williston Basin deposits in Saskatchewan, Canada. The Paradox Basin in Utah contains resources of about 2 billion tons, mostly at depths of more than 1,200 meters. The Holbrook Basin of Arizona contains resources of about 1 billion tons. A large potash resource lies about 2,100 meters under central Michigan. The U.S. reserves figure above includes approximately 40 million tons in central Michigan. Estimated world resources total about 250 billion tons.


There are no substitutes for potassium as an essential plant nutrient and an essential nutritional requirement for animals and humans. Manure and glauconite (greensand) are low-potassium-content sources that can be profitably transported only short distances to the crop fields.

See also:

Arizona Geologic History: Chapter 1, Precambrian Time When Arizona was at the South Pole

Arizona Geological History: Chapter 2, Cambrian and Ordovician Time

Arizona Geological History: Chapter 3: Devonian to Permian Time

Arizona Geological History Chapter 4: Triassic Period

Arizona Geological History Chapter 5: Jurassic Time

Arizona Geological History 6, The Cretaceous Period

Arizona Geological History 7: The Cenozoic Era