The mining industry of New Mexico dates back to the days of Spanish
rule. Copper was mined from the Santa Rita mine as early as 1800 for
shipment to Mexico for use in coinage. Significant mining in New Mexico
did not commence, however, until the late 1800’s. There are three major
centers today: Carlsbad, potash; Silver City area, copper, zinc, and
lead; and Grants, uranium.
[Illustration: Question: where are the other oil pumps and tanks in
the San Juan Basin?]
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.
[Illustration: (_Courtesy International Minerals & Chemical Corp._)
Crunch!... continuous mining machine at work]
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.
[Illustration: (_Courtesy The Anaconda Co._)
Man, dig this hole!... Jackpile open-pit uranium mine near Laguna]
[Illustration: (_Courtesy Kennecott Copper Corp._)
“Just scoop up copper ore, take it to the skipway....” up the side
of the Chino Mine at Santa Rita]
Copper, potash, and uranium are not the only mining operations of New
Mexico. Perlite is recovered from deposits near No Agua in Taos County
and just north of Grants. Two new gypsum plants are now operating
northeast of Albuquerque, and a cement plant is located east of that
city. High-grade copper veins are worked south of Lordsburg. Coal mining
is being reactivated, with producing mines near Gallup, Fruitland, and
Raton. A new molybdenum mine is under development east of Questa. New
Mexico’s mineral industry is on a broad and firm base.
Mines and derricks are ever-present aspects of New Mexico’s landscapes;
they are seen by every citizen of the state and every tourist as he
travels across the plains, valleys, and mountains. The derricks and the
mine openings are merely surface features through which the vast wealth
of the underground is exploited, but they are a monetarily important
part of New Mexico’s scenery, rocks, and history.