The potash mining east of Carlsbad, a $75 million-a-year industry employing more than 3600 persons, is the largest operation of its kind in the world. Six mining companies are active in the area, and a seventh is developing yet another mine. Potash is a word used to denote various potassium compounds. The principal ore mineral at Carlsbad is sylvanite, a mixture of potassium chloride and sodium chloride (common salt). The ore contains the equivalent of 21 to 25 per cent potassium oxide (K2O).[6] Another ore mineral, known as langbeinite, a double salt of potassium and magnesium sulfate, is also mined.

The potash ores occur as horizontal beds sandwiched between thick salt and anhydrite layers. These beds are the result of evaporation of large quantities of salt waters during the latter part of the Permian period some 240 million years ago. The potash-bearing horizons now are buried from 900 to 1800 feet below the surface. The discovery of potash in southeast New Mexico was almost by accident. In 1925, the Snowden and McSweeny Company drilled a wildcat oil test a few miles east of Carlsbad. The hole was dry, but potash minerals were detected in the drill cuttings. The discovery generated considerable interest because the United States was forced to import most of its potash prior to this time. Further drilling proved the existence of tremendous deposits of potassium salts in that area.

The potash mines are among the most highly mechanized of the mineral industry. Access to the buried deposits is gained by vertical shafts. Actual mining is now done to a large extent by continuous miners, machines which bore or rip the potash ore from the face and load it into shuttle cars in one continuous operation. The shuttle cars then transport the ore to conveyor belts which move it to the shafts for hoisting. Working conditions and safety are excellent and have led to high productivity from these mines.

The potash ore is refined or processed by fractional crystallation or flotation. These plants remove most of the unwanted sodium chloride and other gangue minerals to produce high-quality potassium chloride or sulfate. After processing, the potash salts are stored in giant bins to await shipment by rail to the major agriculture areas of the United States. The Carlsbad mines produce some 15 million tons of ore a year which, when refined, produces 4 million tons of marketable potassium salts having a K2O equivalent of 2.5 million tons.

Uranium mining is the newest major industry in New Mexico. The boom started in 1950 with the discovery of uranium ore west of Grants by a Navajo sheep rancher named Paddy Martinez. This discovery started one of the most extensive exploration and development campaigns in all mining history. By 1957, the area had proved uranium reserves accounting for more than half of the entire reserve of the nation. These discoveries will make this country self-sufficient in this vital atomic energy metal for years to come. Five mills were built that are capable of producing “yellow cake” (almost pure uranium oxide) from uranium ores containing as little as 0.20 per cent U3O8. Four mills are located in the Grants area, ranging in capacity from 1500 to 4000 tons a day. The fifth mill, rated at 500 tons a day, is at Shiprock.

There are numerous mines, ranging from tiny two-man operations up to great mines producing more than 1000 tons a day. The most prolific producing area is the Ambrosia Lake District north of Grants; most of these mines are underground. Probably the largest single uranium mine, however, is the open-pit Jackpile-Paguate mine of the Anaconda Company on the Laguna Indian Reservation some thirty miles east of Grants. The mine uses electric shovels capable of loading eight cubic yards of ore at a time into large diesel trucks.

Copper is produced from the Chino mine located at Santa Rita, about fifteen miles east of Silver City. This mine, operated by Kennecott Copper Corporation, is the showpiece of the New Mexico minerals industry. The copper ore is low grade, containing only sixteen pounds a ton of the red metal, but the deposit is immense, allowing the mining of 22,500 tons a day. The Chino is by far the largest single mining operation in the state. A large concentrator and smelter are located at Hurley, about ten miles southwest of the pit.

The Chino pit is a spectacular sight for its scenic setting and its sheer size. The deposit is located below the Kneeling Nun, a famous natural statue formed by the erosion of a rhyolite flow which caps a high mesa. The pit covers almost one square mile and is 800 feet deep. The mining is highly mechanized. Large rotary drills make blast holes twelve inches in diameter into which explosives are loaded. A single blast may break 100,000 tons of rock. The ore is loaded with 8-cubic-yard shovels into large trucks carrying from 25 to 65 tons each. The trucks transport the ore to an inclined skipway on the west end of the pit. The skip then carries the ore up to the train level where it is transferred into railroad cars for shipment to the mill. Waste rock, too low-grade to justify sending to the mill, is transported to the very top of the skip way, where it is trucked to the dumps. At Chino, much of the waste rock contains some copper. The amount is small, but a part of it can be recovered by leaching-percolating water down through the rock to dissolve the copper. At the bottom of the dumps, the copper-rich water is collected and sent through precipitating tanks containing scrap iron. The copper plates out on the iron, forming metallic copper. The dump-leaching program alone at Chino is a substantial enterprise.

The concentrator and smelter at Hurley is the facility which reduces the low-grade ore into pure metal. The concentrator first crushes and grinds the ore, then recovers the copper-bearing minerals (principally chalcocite and chalcopyrite) by flotation. The concentrate of these copper sulfides is taken to the smelter to make metallic copper.

North and west of the Chino mine are important deposits of zinc and lead. Two underground mines are now active: the Hanover of the New Jersey Zinc Company and the Kearney—Pewabic of American—Peru Mining Company. Although dwarfed by the Chino mine, these are important producers.