San Manuel Copper Mine
Encyclopedia
The San Manuel Copper Mine was a surface and underground porphyry copper mine located in San Manuel
, Pinal County, Arizona
. Frank Schultz was the original discoverer, in 1879, but the main body of the deposits were discovered by Henry W. Nichols in 1942. The exploration drilling went on from 1943 to 1948, with the first mine shaft built 1948. Louis Lesser
developed a mining city to service Nichols’ newly discovered deposits, and the development was completed about 1954. The first major production began in 1955, and the mine and smelter were permanently closed in 2003.
is a porphyry copper deposit
, with the ore body being tabular and 300 metres (984.3 ft) thick. The Kalamazoo ore body is U-shaped, with a depth of 1140 metres (3,740.2 ft) to the top.
The mineralization is related to a Laramide
monzonite
porphyry
stock and associated dikes
which were intruded
into existing Precambrian
quartz monzonite body. Mineralization occurs within the Laramide intrusive and in the surrounding Precambrian porphyry.
The Kalamazoo portion of the deposit was discovered by an exploration drilling program based on the missing portion of the presumed symmetrical hydrothermal alteration/mineralization pattern of the San Manuel portion of the deposit. Geologist J. D. Lowell who directed the program and John M. Guilbert went on to develop this work into a general pattern for porphyry copper deposit exploration.
, which ultimately closed it. Over 700,000,000 tons of ore were extracted using the block caving method. It was a large disseminated copper sulfide deposit mined with five shafts each over 3000 feet (914.4 m) deep. Headframes are over 60 metres (196.9 ft) high. The operation of mining was divided into mining the hypogene sulfide mineralization (chalcopyrite
) at depth and the shallow supergene
(chalcocite
) and oxidized deposit (chrysocolla
, malachite
, native copper
and cuprite
).
The entire large site is now scheduled for reclamation.
San Manuel, Arizona
San Manuel is a census-designated place in Pinal County, Arizona, United States. The population was 4,375 at the 2000 census.San Manuel was built in 1953 as a company town to serve the then-new San Manuel copper mine, mill and smelter complex. The mine and smelter were permanently closed in...
, Pinal County, Arizona
Pinal County, Arizona
-2010:Whereas according to the 2010 U.S. Census Bureau:*72.4% White*4.6% Black*5.6% Native American*1.7% Asian*0.4% Native Hawaiian or Pacific Islander*3.8% Two or more races*11.5% Other races*28.5% Hispanic or Latino -2000:...
. Frank Schultz was the original discoverer, in 1879, but the main body of the deposits were discovered by Henry W. Nichols in 1942. The exploration drilling went on from 1943 to 1948, with the first mine shaft built 1948. Louis Lesser
Louis Lesser
Louis Lesser is an American business magnate. He received frequent press coverage in the 1950s and 1960s for his ability to earn money and for his various business operations. He sold the Taj Mahal to New York real estate developer Donald Trump...
developed a mining city to service Nichols’ newly discovered deposits, and the development was completed about 1954. The first major production began in 1955, and the mine and smelter were permanently closed in 2003.
Geology
Faulting of the original ore body created two main segments, separated by an area of minor sulfides. The original ore body was cylindrical, but the San Manuel fault caused the division into two main parts, called the upper San Manuel ore body and the lower Kalamazoo ore body. The bodies are now separated by about 8000 feet (2,438.4 m) The mineralized zone that contains the ore deposit is about 8000 feet (2,438.4 m) to 9000 feet (2,743.2 m) wide, and more than 9300 feet (2,834.6 m) long, trending east-north-east. The mineralizationMineralization (geology)
In geology, mineralization is the hydrothermal deposition of economically important metals in the formation of ore bodies or "lodes".The first scientific studies of this process took place in Cornwall, United Kingdom by J.W.Henwood FRS and later by R.W...
is a porphyry copper deposit
Porphyry copper deposit
Porphyry copper deposits are copper orebodies which are associated with porphyritic intrusive rocks and the fluids that accompany them during the transition and cooling from magma to rock. Circulating surface water or underground fluids may interact with the plutonic fluids...
, with the ore body being tabular and 300 metres (984.3 ft) thick. The Kalamazoo ore body is U-shaped, with a depth of 1140 metres (3,740.2 ft) to the top.
The mineralization is related to a Laramide
Laramide orogeny
The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute, as is the cause. The Laramide...
monzonite
Monzonite
Monzonite is an intermediate igneous intrusive rock composed of approximately equal amounts of sodic to intermediate plagioclase and orthoclase feldspars with minor amounts of hornblende, biotite and other minerals...
porphyry
Porphyry copper deposit
Porphyry copper deposits are copper orebodies which are associated with porphyritic intrusive rocks and the fluids that accompany them during the transition and cooling from magma to rock. Circulating surface water or underground fluids may interact with the plutonic fluids...
stock and associated dikes
Dike (geology)
A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
which were intruded
Intrusion
An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
into existing Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
quartz monzonite body. Mineralization occurs within the Laramide intrusive and in the surrounding Precambrian porphyry.
The Kalamazoo portion of the deposit was discovered by an exploration drilling program based on the missing portion of the presumed symmetrical hydrothermal alteration/mineralization pattern of the San Manuel portion of the deposit. Geologist J. D. Lowell who directed the program and John M. Guilbert went on to develop this work into a general pattern for porphyry copper deposit exploration.
Operation
The mine was operated by the Magma Copper Company before being bought out by BHP BillitonBHP Billiton
BHP Billiton is a global mining, oil and gas company headquartered in Melbourne, Australia and with a major management office in London, United Kingdom...
, which ultimately closed it. Over 700,000,000 tons of ore were extracted using the block caving method. It was a large disseminated copper sulfide deposit mined with five shafts each over 3000 feet (914.4 m) deep. Headframes are over 60 metres (196.9 ft) high. The operation of mining was divided into mining the hypogene sulfide mineralization (chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
) at depth and the shallow supergene
Supergene (geology)
In ore deposit geology, supergene processes or enrichment occur relatively near the surface. Supergene processes include the predominance of meteoric water circulation with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary sulfide ore minerals and...
(chalcocite
Chalcocite
Chalcocite, copper sulfide , is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system....
) and oxidized deposit (chrysocolla
Chrysocolla
Chrysocolla is a hydrated copper silicate mineral with formula 2H2Si2O54·nH2O.-Properties:Chrysocolla has a blue-green color and is a minor ore of copper, having a hardness of 2.5 to 3.5.-Name and discovery:...
, malachite
Malachite
Malachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
, native copper
Native copper
Copper, as native copper, is one of the few metallic elements to occur in uncombined form as a natural mineral, although most commonly occurs in oxidized states and mixed with other elements...
and cuprite
Cuprite
Cuprite is an oxide mineral composed of copper oxide Cu2O, and is a minor ore of copper.Its dark crystals with red internal reflections are in the isometric system hexoctahedral class, appearing as cubic, octahedral, or dodecahedral forms, or in combinations. Penetration twins frequently occur...
).
The entire large site is now scheduled for reclamation.
Technical reports
- Buchanan, John F. and Buchella, Frank H., “History and Development of the San Manuel Mine". A.I.M.E. Vol. 217, February 1960
- Chapman, T. L., “San Manuel copper deposit, Pinal Co., Arizona”, US Bureau of Mines Report of Investigation 4108, 1947
- Dale, V. B., “Mining, milling, and smelting methods”, San Manuel Copper Corp., Pinal County, Arizona: U.S. Bureau of Mines Information Circular I.C. 8104, 145 p., 1962
- Galbraith, F.W., 1947, “Minerals of Arizona”, Arizona Bureau of Mines Bulletin 153: 19, 1947
- Lovering, T. S., “Dispersion of copper from the San Manuel copper deposit, Pinal Co., Arizona”, Economic Geology: 45: 493-514, 1950
- Lovering, T. S., “Geothermal gradients, recent climate changes, and rate of sulphide oxidation in the San Manuel district, Arizona”, Economic Geology: 43: 1-20, (1948)
- Schwartz, G. M., “Hydrothermal alteration in the 'porphyry copper' deposits”, Economic Geology: 42: 319-352, 1947
- Schwartz. G. M., “Geology of the San Manuel copper deposit, Arizona”, USGS PP 256, 1953
- Schwartz, G. M., “Oxidation and enrichment in the San Manuel copper deposit, Arizona”, Economic Geology: 44: 253-277, 1949
Books
- Tafoya, Onofre, “Mother Magma, A Memoir of Underground Life in the San Manuel Copper Mine," Hispanic Institute of Social Issues, 2006 ISBN 978-0977116768