Iron Mountain Mine
Encyclopedia
Iron Mountain Mine, also known as the Richmond Mine at Iron Mountain, is a mine
near Redding
in Northern California
. Geologically classified as a "massive sulfide
ore
deposit", the site was mined for iron
, silver
, gold
, copper
, zinc
, and pyrite
intermittently from the 1860s until 1963. The mine is the source of extremely acidic mine drainage
which also contains large amounts of zinc
, copper
and cadmium
. One of America's most toxic waste sites, it has been listed as a federal Superfund
site since 1983.
and sidehill mining. As a result, the mountain fractured and mineral deposits were exposed to oxygen, water and certain bacteria, resulting in acidic mine drainage.
Though mining operations were discontinued in 1963, underground mine workings, waste rock dumps, piles of mine tailings, and an open mine pit still remain at the site. Historic mining activity at IMM has fractured the mountain, exposing minerals in the mountain to surface water, rain water, and oxygen. When pyrite is exposed to moisture and oxygen, sulfuric acid forms. This sulfuric acid runs through the mountain and leaches out copper, cadmium, zinc, and other heavy metals. This acid flows out of the seeps and portals of the mine. Much of the acidic mine drainage ultimately is channeled into the Spring Creek Reservoir by creeks surrounding the mine. The Bureau of Reclamation periodically releases the stored acid mine drainage into Keswick Reservoir. Planned releases are timed to coincide with the presence of diluting releases of water from Shasta Dam
. On occasion, uncontrolled spills and excessive waste releases have occurred when Spring Creek Reservoir
reached capacity. Without sufficient dilution, this results in the release of harmful quantities of heavy metals into the Sacramento River
. Approximately 70,000 people use surface water within 3 miles as their source of drinking water. The low pH level and the heavy metal contamination from the mine have caused the virtual elimination of aquatic life in sections of Slickrock Creek, Boulder Creek
, and Spring Creek
.
The mine was designated a Superfund site in 1983 and a water treatment plant was built in 1994. In 2000 the government reached a settlement with Aventis CropScience (now part of Bayer
) for the long-term funding of the cleanup efforts.
The mine is located at 40°40′20"N 122°31′40"W in the Klamath Mountains
of Shasta County
, about 9 miles northwest of Redding. The mine area is drained by several creeks which ultimately enter the Spring Creek Reservoir, formed by the Spring Creek Dam
, and finally the Keswick Reservoir formed by a dam across the Sacramento River
. This reservoir is a major source of drinking water for Redding.
The drainage water from the Iron Mountain Mine is the most acid
ic water naturally found on Earth; some samples collected in 1990 and 1991 have been measured to have a pH
value of -3.6. The drainage water endangers fish, including winter-run Chinook salmon
, a federally listed endangered species
that spawns in the Sacramento River. Salmon kills have been noted since 1899.
The mine opening contains huge stalactite
-stalagmite
structures that span from floor to ceiling and are composed of rhomboclase
and other iron sulfate minerals.
and archaea
living in the mine are of interest because they can survive in this extreme environment, and because their metabolism
contributes to the pollution. They form a pink biofilm
several millimeters thick that floats on the surface of the hot water with a pH of 0.8. Since the bacteria cannot be isolated and cultured, scientists have performed community sequencing
of the DNA
of the five dominant species at once, assembling the genomes afterwards. Four new species were identified in this way in 2004. In 2005 the protein
s produced by these bacteria were identified; of the 2033 found proteins 572 were unique to this biofilm. In 2006, Baker identified three novel archaea, the Archaeal Richmond Mine Acidophilic Nanoorganisms
.
The bacteria obtain carbon
from the air's carbon dioxide
and nitrogen
from the air's N2 gas. They are aerobes and obtain energy by using oxygen
to oxidize ferrous iron
dissolved from the iron sulfide
rock; in the process they produce sulfuric acid
which releases more metals from the rock.
The bacteria belong to the group of acidophilic
ferrous iron oxidizers.
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
near Redding
Redding, California
Redding is a city in far-Northern California. It is the county seat of Shasta County, California, USA. With a population of 89,861, according to the 2010 Census...
in Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
. Geologically classified as a "massive sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
deposit", the site was mined for iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, and pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
intermittently from the 1860s until 1963. The mine is the source of extremely acidic mine drainage
Acid mine drainage
Acid mine drainage , or acid rock drainage , refers to the outflow of acidic water from metal mines or coal mines. However, other areas where the earth has been disturbed may also contribute acid rock drainage to the environment...
which also contains large amounts of zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
and cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
. One of America's most toxic waste sites, it has been listed as a federal Superfund
Superfund
Superfund is the common name for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 , a United States federal law designed to clean up sites contaminated with hazardous substances...
site since 1983.
History
The site was mined by the Mountain Copper Company, Ltd., both underground using open stope mining techniques and at the surface in the form of open pitOpen-pit mining
Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow....
and sidehill mining. As a result, the mountain fractured and mineral deposits were exposed to oxygen, water and certain bacteria, resulting in acidic mine drainage.
Though mining operations were discontinued in 1963, underground mine workings, waste rock dumps, piles of mine tailings, and an open mine pit still remain at the site. Historic mining activity at IMM has fractured the mountain, exposing minerals in the mountain to surface water, rain water, and oxygen. When pyrite is exposed to moisture and oxygen, sulfuric acid forms. This sulfuric acid runs through the mountain and leaches out copper, cadmium, zinc, and other heavy metals. This acid flows out of the seeps and portals of the mine. Much of the acidic mine drainage ultimately is channeled into the Spring Creek Reservoir by creeks surrounding the mine. The Bureau of Reclamation periodically releases the stored acid mine drainage into Keswick Reservoir. Planned releases are timed to coincide with the presence of diluting releases of water from Shasta Dam
Shasta Dam
Shasta Dam is an arch dam across the Sacramento River in the northern part of the U.S. state of California, at the north end of the Sacramento Valley. The dam mainly serves long-term water storage and flood control in its reservoir, Shasta Lake, and also generates hydroelectric power...
. On occasion, uncontrolled spills and excessive waste releases have occurred when Spring Creek Reservoir
Spring Creek Reservoir (California)
The Spring Creek Reservoir is the artificial lake created by the construction of the Spring Creek Dam across Spring Creek in the Shasta-Trinity National Forest of Shasta County, California, adjacent to Keswick....
reached capacity. Without sufficient dilution, this results in the release of harmful quantities of heavy metals into the Sacramento River
Sacramento River
The Sacramento River is an important watercourse of Northern and Central California in the United States. The largest river in California, it rises on the eastern slopes of the Klamath Mountains, and after a journey south of over , empties into Suisun Bay, an arm of the San Francisco Bay, and...
. Approximately 70,000 people use surface water within 3 miles as their source of drinking water. The low pH level and the heavy metal contamination from the mine have caused the virtual elimination of aquatic life in sections of Slickrock Creek, Boulder Creek
Boulder Creek
Boulder Creek may be:*A community:**Boulder Creek, California*One of several streams:**Boulder Creek in Santa Cruz County**Boulder Creek in San Diego County**Boulder Creek **Boulder Creek...
, and Spring Creek
Spring Creek
A spring creek is a stream that flows from a spring. Spring Creek may also refer to any of the following specific places:- United States :*Spring Creek Correctional Center, a state prison in Seward, Alaska...
.
The mine was designated a Superfund site in 1983 and a water treatment plant was built in 1994. In 2000 the government reached a settlement with Aventis CropScience (now part of Bayer
Bayer
Bayer AG is a chemical and pharmaceutical company founded in Barmen , Germany in 1863. It is headquartered in Leverkusen, North Rhine-Westphalia, Germany and well known for its original brand of aspirin.-History:...
) for the long-term funding of the cleanup efforts.
Location and drainage
Klamath Mountains
The Klamath Mountains, which include the Siskiyou, Marble, Scott, Trinity, Trinity Alps, Salmon, and northern Yolla-Bolly Mountains, are a rugged lightly populated mountain range in northwest California and southwest Oregon in the United States...
of Shasta County
Shasta County, California
Shasta County is a county located in the northern portion of the U.S. state of California. The county occupies the northern reaches of the Sacramento Valley, with portions extending into the southern reaches of the Cascade Range. As of the 2010 census, the population was 177,223, up from 163,256...
, about 9 miles northwest of Redding. The mine area is drained by several creeks which ultimately enter the Spring Creek Reservoir, formed by the Spring Creek Dam
Spring Creek Dam
The Spring Creek Debris Dam is an earthfill dam on Spring Creek, a tributary of the Sacramento River, in Shasta County in the U.S. state of California. Completed in 1963, the dam, maintained by the U.S. Bureau of Reclamation, serves primarily to collect severe acid mine drainage stemming from the...
, and finally the Keswick Reservoir formed by a dam across the Sacramento River
Sacramento River
The Sacramento River is an important watercourse of Northern and Central California in the United States. The largest river in California, it rises on the eastern slopes of the Klamath Mountains, and after a journey south of over , empties into Suisun Bay, an arm of the San Francisco Bay, and...
. This reservoir is a major source of drinking water for Redding.
The drainage water from the Iron Mountain Mine is the most acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ic water naturally found on Earth; some samples collected in 1990 and 1991 have been measured to have a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
value of -3.6. The drainage water endangers fish, including winter-run Chinook salmon
Chinook salmon
The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific salmon family. Other commonly used names for the species include King salmon, Quinnat salmon, Spring salmon and Tyee salmon...
, a federally listed endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
that spawns in the Sacramento River. Salmon kills have been noted since 1899.
The mine opening contains huge stalactite
Stalactite
A stalactite , "to drip", and meaning "that which drips") is a type of speleothem that hangs from the ceiling of limestone caves. It is a type of dripstone...
-stalagmite
Stalagmite
A stalagmite is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate. This stalagmite formation occurs only under certain pH conditions within the underground cavern. The corresponding formation on...
structures that span from floor to ceiling and are composed of rhomboclase
Rhomboclase
Rhomboclase is an acidic iron sulfate mineral with a formula reported as H5Fe3+O22·2 or HFe2·4. It crystallizes in the orthorhombic system and typically occurs as tabular crystals with a rhombic outline...
and other iron sulfate minerals.
Bacteria and Archaea
The bacteriaBacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and archaea
Archaea
The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...
living in the mine are of interest because they can survive in this extreme environment, and because their metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
contributes to the pollution. They form a pink biofilm
Biofilm
A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance...
several millimeters thick that floats on the surface of the hot water with a pH of 0.8. Since the bacteria cannot be isolated and cultured, scientists have performed community sequencing
Shotgun sequencing
In genetics, shotgun sequencing, also known as shotgun cloning, is a method used for sequencing long DNA strands. It is named by analogy with the rapidly-expanding, quasi-random firing pattern of a shotgun....
of the DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
of the five dominant species at once, assembling the genomes afterwards. Four new species were identified in this way in 2004. In 2005 the protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s produced by these bacteria were identified; of the 2033 found proteins 572 were unique to this biofilm. In 2006, Baker identified three novel archaea, the Archaeal Richmond Mine Acidophilic Nanoorganisms
Archaeal Richmond Mine Acidophilic Nanoorganisms
Archaeal Richmond Mine acidophilic nanoorganisms were first discovered in an extremely acidic mine located in northern California by Brett Baker in Jill Banfield's laboratory at the University of California Berkeley...
.
The bacteria obtain carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
from the air's carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
from the air's N2 gas. They are aerobes and obtain energy by using oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
to oxidize ferrous iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
dissolved from the iron sulfide
Iron sulfide
Iron sulfide or Iron sulphide refers to a chemical compound of iron and sulfur with a wide range of stoechiometric formulae and different crystalline structures.-Natural minerals:By increasing order of stability:...
rock; in the process they produce sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
which releases more metals from the rock.
The bacteria belong to the group of acidophilic
Acidophile (organisms)
Acidophilic organisms are those that thrive under highly acidic conditions . These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukaryotes...
ferrous iron oxidizers.
External links
- Information and links about Iron Mountain Mine, from the Toxic Substances Hydrology Program of the USGS
- US EPA Iron Mountain Mine