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{{Short description|Adit mine in New Mexico, US}} |
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{{Use mdy dates|date=February 2018}} |
{{Use mdy dates|date=February 2018}} |
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{{Infobox mine |
{{Infobox mine |
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| image = View Looking East from the Harding Pegmatite Mine near Dixon, New Mexico USA 03.jpg |
| image = View Looking East from the Harding Pegmatite Mine near Dixon, New Mexico USA 03.jpg |
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| caption = The Harding Pegmatite |
| caption = The Harding Pegmatite Mine is a former beryl quarry in New Mexico. |
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| pushpin_map = New Mexico |
| pushpin_map = New Mexico |
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| pushpin_mapsize = 180 |
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| coordinates = {{coord|36. |
| coordinates = {{coord|36.1928|N|105.7946|W|region:US-UT_scale:100000|format=dms|display=inline,title}} |
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| place = [[Picuris Mountains]] |
| place = [[Picuris Mountains]] |
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| subdivision_type = State |
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| type = [[Adit|Adit mine]] |
| type = [[Adit|Adit mine]] |
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| amount = <!--include units--> |
| amount = <!--include units--> |
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| opening year = {{Start date|1906}} |
| opening year = {{Start date and age|1906}} |
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| active years = <!-- use only if inactive for a period of time--> |
| active years = <!-- use only if inactive for a period of time--> |
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| closing year = |
| closing year = {{End date and age|1958}} |
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| discovery year = 1918 |
| discovery year = {{Start date and age|1918}} |
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| owner = |
| owner = [[University of New Mexico]] |
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| official website = <!-- {{URL|example.com}} --> |
| official website = <!-- {{URL|example.com}} --> |
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| acquisition year = |
| acquisition year = {{Start date and age|1979}}<ref name="bccelr1979">{{cite journal |last1=Brookins |first1=Douglas G. |last2=Chakoumakos |first2=Bryan C. |last3=Cook |first3=Clarence W. |last4=Ewing |first4=Rodney C. |last5=Landis |first5=Gary P. |last6=Register |first6=Marcia E. |title=THE HARDING PEGMATITE: SUMMARY OF RECENT RESEARCH |journal=New Mexico Geological Society Field Conference Series |date=1979 |volume=30 |page=127 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/30/30_p0127_p0133.pdf |access-date=16 April 2020}}</ref> |
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| nrhp = |
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}} |
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The '''Harding Pegmatite Mine''' is a former [[Adit|adit mine]] that extracted [[lithium]], [[tantalum]], and [[beryllium]] from a [[Precambrian]] [[pegmatite]] [[sill]]. It ceased operations in 1958 and its owner, Arthur Montgomery, |
The '''Harding Pegmatite Mine''' is a former [[Adit|adit mine]] that extracted [[lithium]], [[tantalum]], and [[beryllium]] from a [[Precambrian]] [[pegmatite]] [[Sill (geology)|sill]]. It ceased operations in 1958 and its owner, Arthur Montgomery, donated it to the [[University of New Mexico]], which runs the site as an outdoor geology laboratory with mineral collecting permitted on a small scale.<ref name="je1976">{{cite journal |last1=Jahns |first1=Richard H. |last2=Ewing |first2=Rodney C. |title=The Harding Mine Taos County New Mexico |journal=New Mexico Geological Society Field Conference Series |date=1976 |volume=27 |page=263 |url=https://earth315.earth.lsa.umich.edu/Earth_315_Field_Trip_-_New_Mexico/References_files/Jahns76_NWGS_HardingMine.pdf}}</ref><ref name="bccelr1979"/> |
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[[File:Harding Mine.jpg|thumb|Main quarry of Harding Pegmatite Mine]] |
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==History== |
==History== |
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Although the quartz pegmatite had attracted the attention of prospectors since before 1900, the extensive deposits of [[lepidolite]] were not recognized until 1918 by Joseph J. Peyer. Peyer and his partners mined the ore body with explosives, sorted the ore by hand, and hauled the ore to [[Embudo, New Mexico|Embudo]] by wagon, where the nearest rail line was located. At that time, the chief use of lithium was in specialty [[glass]]. However, the ore was contaminated with unrecognized [[tantalite]] which caused serious difficulties with its |
Although the quartz pegmatite had attracted the attention of prospectors since before 1900, the extensive deposits of [[lepidolite]] were not recognized until 1918 by Joseph J. Peyer. Peyer and his partners mined the ore body with explosives, sorted the ore by hand, and hauled the ore to [[Embudo, New Mexico|Embudo]] by wagon, where the nearest rail line was located. At that time, the chief use of lithium was in specialty [[glass]]. However, the ore was contaminated with unrecognized [[tantalite]] which caused serious difficulties with its use, and production ceased in 1924. |
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That same year, the Embudo Mining Company was organized by J.L. Danziger and began construction of a mill near Embudo. This was completed and mining resumed in 1927. The main ore body was mined out in 1929 and the mine closed again in 1930. About 3,500 tons of ore were produced with a value of about $140,000. This represented a modest profit over the three years of mill operations but a net loss for the entire period of mining. |
That same year, the Embudo Mining Company was organized by J.L. Danziger and began construction of a mill near Embudo. This was completed and mining resumed in 1927. The main ore body was mined out in 1929 and the mine closed again in 1930. About 3,500 tons of ore were produced with a value of about $140,000. This represented a modest profit over the three years of mill operations but a net loss for the entire period of mining. |
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High demand for tantalum in 1942 for wartime production, and reports going back to 1931 of microlite at the Harding Mine, led Arthur Montgomery to investigate the old workings. He found considerable rich material in the mine dumps and at the east end of the workings, and |
High demand for tantalum in 1942 for wartime production, and reports going back to 1931 of [[microlite]] at the Harding Mine, led Arthur Montgomery to investigate the old workings. He found considerable rich material in the mine dumps and at the east end of the workings, and he obtained a [[lease purchase contract]] on the mine property. With a team of six local miners, ore was extracted with chisels and sorted by hand. Concentration of the small but rich quantity of highly valuable ore was problematic, but the U.S. Bureau of Mines Testing Laboratory in Rolla, Missouri, used an experimental gravity separation method to process 33.5 tons of ore and extracted 6137 pounds of 77.55% niobium-tantalum oxide. This was the largest unit of U.S. tantalum production ever recorded. However, a small mill built at Rinconada failed to meet its rated capacity of 12 tons per day. |
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Lithium ores were also mined during this period, and by the time mining paused in 1947, the mine had yielded 41 tons of high-grade [[spodumene]], 558 tons of [[lepidolite]] ore, nearly 500 pounds of placer tantalite-columbite containing an average of 43% tantalum oxide, and 22,116 pounds of microlite concentrates containing an average of 68% tantalum oxide and 7% niobium oxide. The operations were profitable enough to allow Montgomery to purchase the property outright. |
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[[File:Bingham Canyon Mine, 2018.jpg|thumb|left|200px|The Bingham Canyon Mine, aerial photograph taken June 2018]] |
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During 1943, the U.S. Bureau of Mines drilled 39 exploratory cores south of the main workings. The cores showed enough content of spodumene and tantalum-niobium minerals to be classified as milling-grade ore. This made the Harding the first U.S. pegmatite mine to have blocked-out reserves. These are still in place and could conceivably be mined in the future. |
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[[Beryl]] had been recognized as a minor accessory mineral at the mine from its inception. However, this was so easily confused with the abundant [[albite]] and [[quartz]] of the pegmatite that it was not until 1942 that the U.S. Geological Survey recognized that beryl was abundant at the mine. In 1944 Montgomery found a single block of beryl weighing almost 100 pounds at one of the dumps, then uncovered a lens of beryl at the west end of the workings. This produced 23 tons of ore containing 11% beryllium oxide. However, full-scale beryllium mining did not begin until 1950. Ore production reached a ton per day, in spite of the difficulties of hand sorting the beryl from the nearly indistinguishable feldspar and quartz [[gangue]]. |
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===Landslides=== |
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{{multiple image |
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In 1950 and 1951, beryl production exceeded 150 tons, making New Mexico the leading beryl-producing state. Production averaged 100 tons per year until 1950, when the death of Montgomery's partner, Flaudio Griego, ended mining operations. Operations were simple, using a crew of four men to mine and hand sort the ore, which was taken out on "Beryl", the mine's mule. Production totaled 690 tons of high-grade ore with 11.2% beryllium oxide and 184 tons of lower-grade ore with 5.5% beryllium oxide, as well as small production of lepidolite.<ref name="je1976"/> |
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| image1 = Bingham Canyon Mine Satellite image before Landslide.jpg |
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== Geology == |
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| image2 = Bingham Canyon Mine Satellite image after Landslide.jpg |
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The Harding pegmatite intrudes along the boundary between the [[amphibolite]] and [[schist]] facies of the [[Vadito Group]].<ref name="je1976"/><ref name="jdft2011">{{cite journal |last1=Jones |first1=James V. III |last2=Daniel |first2=Christopher G. |last3=Frei |first3=Dirk |last4=Thrane |first4=Kristine |title=Revised regional correlations and tectonic implications of Paleoproterozoic and Mesoproterozoic metasedimentary rocks in northern New Mexico, USA: New findings from detrital zircon studies of the Hondo Group, Vadito Group, and Marqueñas Formation |journal=Geosphere |date=2011 |volume=7 |issue=4 |pages=974–991 |doi=10.1130/GES00614.1 |url=https://pubs.geoscienceworld.org/geosphere/article-lookup/7/4/974 |access-date=15 April 2020|doi-access=free }}</ref> The various outcroppings form a belt about 2500 feet long and 150 to 500 feet wide. Radiometric ages are somewhat discordant, ranging from 1260 [[Mya (unit)|Mya]] for four Harding [[muscovite]]s to 1350 Mya for a Harding lepidolite. A more recent "average age" is given as 1336 Mya, and discrepancies may be due to contamination from the host rock.<ref name="bccelr1979"/> However, the pegmatite is thought to be up to 100 million years younger than any nearby [[granite]] plutons and does not seem to be genetically associated with any of them. |
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| footer = Bingham Canyon Mine satellite images before (left, July 20, 2011) and after (right, May 2, 2013) a landslide on April 20, 2013 |
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At 9:30 pm on April 10, 2013, a landslide occurred at the mine. Around {{convert|65|–|70|e6m3|e9cuft|sp=us|order=flip}} of dirt and rock thundered down the side of the pit.<ref>{{cite web |url= http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=81364&src=eorss-nh |title= Sizing up the Landslide at Bingham Canyon Mine |work= Earth Observatory |publisher= NASA}}</ref> On the basis that the mine's steep walls made it a high risk for landslides, an interferometric radar system had been previously installed to monitor the ground's stability. As a result of warnings produced by this system, mining operations had been shut down the previous day in anticipation of the slide and there were no injuries.<ref>{{cite news |first1= McKenzie |last1= Romero |first2= Andrew |last2= Adams |url= http://www.deseretnews.com/article/865578042/Kennecott-confirms-significant-landslide-at-Bingham-Canyon-Mine.html |title= Massive landslide stops production at Bingham Canyon Mine |work= Deseret News |date= April 11, 2013}}</ref> The massive slide was expected to cut production of mined copper by {{convert|100,000|t|ST}}.<ref>{{cite news |url= http://me.smenet.org/webContent.cfm?webarticleid=645 |title= Bingham slide could cut output by 110,000 ST |work= Mining Engineering |date= April 17, 2013 |url-status= dead |archiveurl= https://web.archive.org/web/20131003083232/http://me.smenet.org/webContent.cfm?webarticleid=645 |archivedate= October 3, 2013 }}</ref> A second slide caused an evacuation of 100 workers on September 11, 2013.<ref>http://www.deseretnews.com/article/865586245/Movement-at-Bingham-Canyon-Mine-stops-operation-evacuates-100-employees.html?pg=all</ref> |
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The main mine workings are exposed over a length of about 1100 feet and a breadth of up to 250 feet. The pegmatite is zoned subhorizontally into the following zones: |
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===Environmental history=== |
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* At the upper contact with the Vadito amphibolite facies: A white border rind, 1 to 2 inches thick, of fine-grained quartz-albite muscovite pegmatite. |
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According to environmental specialists,{{who|date=December 2018}} the mine has had adverse environmental effects on the habitats of fish and wild animals as well as air and water pollution, creating health hazards to the surrounding public.<ref>{{cite book|last1=Bell and Laurance J. Donnelly.|first1=Fred G.|title=Mining and its Impact on the Environment.|date=2006|publisher=CRC Press}}</ref> Different federal agencies concerned with environmental conservation have used strict legal rules to pressure the subsidiary of Kennecott copper mine to comply with environmental regulations. Since the early 1990s, Kennecott has spent more than $400 million on clean-up efforts on the affected areas to avoid regulatory laws that would have placed them on the Superfund National Priorities List (NPL).<ref>{{cite web|title=Kennecott Utah Copper's South End Removed from the National Priorities List|url=http://www.kennecott.com/library/media/KUC%20South%20End%20Removed%20from%20NPL.pdf|website=www.kennecott.com|publisher=Kennecott|accessdate=June 23, 2014|archive-url=https://web.archive.org/web/20160603174124/http://www.kennecott.com/library/media/KUC%20South%20End%20Removed%20from%20NPL.pdf|archive-date=June 3, 2016|url-status=dead}}</ref> |
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* A continuous layer, typically 1 to 5 feet thick but up to 14 feet thick, of very coarse quartz, albite, and muscovite. This zone also contains [[microcline]], and has abundant accessory [[apatite]], beryl, and tantalite. Beryl is occasionally very coarse and abundant. |
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* A continuous layer of massive quartz, typically 2 to 8 feet in thickness, but up to 20 to 35 feet. This zone is also rich in muscovite, microcline, and [[cleavelandite]]. |
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[[File:Hadring Mine quartz zone.jpg|thumb|Massive quartz zone of the Harding Mine showing adits]] |
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* A spectacular quartz and lath-spodumene zone. This zone is typically 6 to 20 feet thick but locally fills the entire interior of the dike to a thickness of 20 to 40 feet. The spodumene occurs as blade-like crystals, sometimes of enormous size, mostly oriented at random but sometimes arranged to form a comb-like structure. Accessory minerals are beryl, apatite, microcline, and tantalum-niobium minerals, especially in the lower part of this zone. There is some [[Pseudomorph|pseudomorphic]] replacement of spodumene by rose muscovite and quartz by cleavelandite. |
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[[File:Harding quarz rose muscovite zone.jpg|thumb|Quartz/rose muscovite zone of the Harding zoned pegmatite]] |
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* The core of the dike, known as "spotted rock", which is relatively fine-grained spodumene, microcline, and quartz, with accompanying finer-grained albite, lithium-bearing muscovite, lepidolite, microlite, and tantalite. Much of the spodumene and microcline have been extensively corroded and replaced by fine-grained micas. |
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[[File:Harding spotted rock.jpg|thumb|"Spotted rock" of the Harding pegmatite]] |
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These zones are mirrored at the base of the pegmatite, except that the lower zones tend to be poorer in beryl and more [[aplite|aplitic]] than pegmatitic. The abundant fine-grained albite is sugary in appearance. |
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The figure below shows a comparison of two satellite images used to identify the changes in the Bingham Canyon Mine between 1985 and 2016 |
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[[File:Harding aplite.jpg|thumb|Aplite zone at the Harding Mine]] |
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[https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=33fa9840-0222-11e7-8f66-0edaf8f81e27] |
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<ref>{{cite web|title=Website Omar Alminagorta List|url=http://omaralminagorta.weebly.com/|accessdate=March 6, 2017}}</ref> |
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Additional accessory minerals, of no economic importance but of interest to mineral collectors, include [[almandine]], [[spessartine]], and [[pyrochlore]].<ref name="je1976"/> |
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{{Clear}} |
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<gallery> |
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==Geology== |
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File:View Looking East from the Harding Pegmatite Mine near Dixon, New Mexico USA 02.jpg|Massive quartz pegmatite |
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[[File:BinghamCynX-Section.jpg|thumb|right|Cross-section through open pit, showing ore zonation|300px]] |
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File:Muscovite-157168.jpg|Lithium muscovite |
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[[File:BinghamCynGeologyMap.jpg|thumb|300px|Geologic map showing bedrock geology and alteration zones, USGS.]] |
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File:Piemontite-Zoisite-261789.jpg|Unusual piemontite-zoisite |
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The Bingham Canyon ore deposits occur in the Bingham [[nappe]]. They are a [[porphyry copper deposit]], formed by a [[quartz monzonite]] [[porphyry (geology)|porphyry]] intruded into sedimentary rocks. They exhibit a concentric alteration pattern and mineralogic zonation around the Bingham [[stock (geology)|stock]]. These zones include a central core containing [[magnetite]], followed by "a [[molybdenite]] zone low in copper, a [[bornite]]-[[chalcopyrite]]-gold higher grade copper zone, a [[pyrite]]-chalcopyrite zone, a pyrite zone, and an outermost lead-zinc zone."<ref name=Tooker/>{{rp|E1,E8}} |
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File:Harding Mine Cleavelandite.jpg|Cleavelandite |
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File:Harding Mine apatite.jpg|Apatite |
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</gallery> |
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Geochemical analysis and analysis of fluid inclusions suggests the pegmatite was injected at temperatures near 600 °C at a depth of 6.0 to 7.5 km (2.0 to 2.5 kbar). The primary zones crystallized under closed-system conditions a temperature of 525 to 425 °C. A separate immiscible CO<sub>2</sub>-H<sub>2</sub>O volatile-rich fluid was present in the pegmatite system during crystallization of the primary pegmatite zones. The sugary albite zone formed from a residual Na-rich magma as a response to late-stage pressure release. Saline brines caused lepidolite replacement at temperatures near 265 °C. Finally, small pockets of quartz, feldspar and microlite were crystallized. |
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[[Structural geology|Structurally]], Late [[Paleozoic]] rocks were [[thrust fault]]ed over the [[Precambrian]] [[craton]] during the [[Cretaceous]] [[Sevier orogeny]]. These rocks were later [[intrusive rock|intruded]] and altered in the [[Tertiary]] by [[granitoid]] rocks. This [[igneous]] event was the source of deposition of gold, silver and other [[base metal]]s.<ref name=Tooker/>{{rp|E4}} |
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==Ownership== |
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Copper and molybdenum [[sulfide minerals]] are dispersed in the intruded stock and in the adjoining carbonate sedimentary [[skarn]]s. The main [[stratigraphic]] rocks in Bingham Canyon are Upper [[Pennsylvanian (geology)|Pennsylvanian]] [[sandstone]]s, [[quartzite]]s, and [[limestone]]s known as the Bingham Mine [[formation (geology)|Formation]] in the Oquirrh Group. The central porphyry ores formed from [[mantle (geology)|mantle]] [[hydrothermal circulation]] while the outer [[vein (geology)|vein]] and deposits in the [[sedimentary]] rocks formed at lower temperature when [[magmatic]] and [[meteoric water]]s mixed.<ref name=Tooker/> |
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In 1974, Arthur Montgomery offered to donate the property to the University of New Mexico. The university leased the property for four years while making numerous improvements, which include a walking tour of the mine. Because the mine property included both patented and unpatented claims, transfer of the title required an act of Congress (Senate Bill 1403). The United States retains the right to mine strategic minerals should it become necessary for the security of the United States. |
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Persons wishing to visit the mine must contact the chairman, Department of Geology, University of New Mexico, 87131 to obtain permission (which is almost always granted) and release forms.<ref name="bccelr1979"/> |
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==Recovery process== |
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The extracted ore is treated at the [[Kennecott Smokestack|Kennecott smelter]] at nearby [[Magna, Utah]]. The ore is run through a concentrator, where huge grinding mills reduce it to the consistency of face powder.<ref>{{Cite book|url=https://books.google.com/books?id=zwRKAQAAMAAJ|title=Bingham Mining: crushing and conveying the ore|date=January 1, 1911|publisher=Mining World Company|language=en}}</ref> [[Flotation process|Flotation]] then separates the [[gangue]] from the metalliferous particles, which float off as a 28-percent concentrate of [[copper]] along with lesser amounts of [[silver]], [[gold]], [[lead]], [[molybdenum]], [[platinum]] and [[palladium]]. A selective flotation step separates the [[molybdenite]] ([[molybdenum disulfide]]) from the [[chalcopyrite]]. |
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The filtered concentrate slurry is piped {{convert|17|mi|km}} to the smelter, where it is dried, and then injected along with oxygen into a flash smelting furnace to oxidize the iron and sulfur. The oxidized iron is skimmed off, while the sulfur dioxide gas is captured and sent to an on-site acid plant for conversion to valuable [[sulfuric acid]] – a million tons of it each year. |
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Left behind is a molten [[copper sulfide]] called matte. The 70-percent-copper matte is water-quenched to form a sand-like solid, then injected, with [[oxygen]], into a flash-converting furnace that produces molten, 98.6-percent-pure copper. This copper is then cast into {{convert|700|lb|kg|adj=on}} anode plates and shipped by rail to the refinery. |
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At the refinery, the [[anode]] plates are pressed flat and interleaved with stainless steel [[cathode]] blanks. Automated robotic vehicles place the prepared anodes in cells containing an acidic [[electrolyte]]. When the cells are electrified, the anodes slowly dissolve, freeing copper ions that are deposited on the cathode as 99.99-percent-pure copper. |
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Impurities and precious metals settle to the bottom of the electrolytic cells as [[anode slime]]s. A [[chlorination reaction|chlorination]] leaching process recovers the gold and silver, which is melted in induction furnaces. |
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== Operations == |
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[[File:Bingham Canyon mine, 1910.jpg|thumb|right|Utah Copper Co. Mill, Bingham Canyon, circa 1910]] |
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Kennecott's Bingham Canyon Mine is the largest artificially made excavation in the world, and is [[Artificial structures visible from space|visible to the naked eye from an orbiting space shuttle]].<ref name="utah.com-kennecott"/><ref name="infomine"/><ref name="rock and gem">{{cite web|url=http://www.rockhounds.com/rockgem/articles/bingham_canyon.html|title=Bingham Canyon Copper: Finding Chalcopyrite at "The Richest Hole on Earth"|first=Steve|last=Voynick|accessdate=July 11, 2010|archive-url=https://web.archive.org/web/20100630105433/http://www.rockhounds.com/rockgem/articles/bingham_canyon.html|archive-date=June 30, 2010|url-status=dead}}</ref> Employing some 2,000 workers, {{convert|450,000|ST|LT t}} of material are removed from the mine daily. Electric shovels can carry up to {{convert|56|cuyd|m3}} or {{convert|98|ST|LT t|0}} of ore in a single scoop. Ore is loaded into a fleet of 64 large [[Dump truck#Off-road dump truck|dump trucks]] which each carry {{convert|255|ST|LT t}} of ore at a time; the trucks themselves cost about $3 million each. There is a {{convert|5|mi|km|0|adj=on|spell=in}} series of conveyors that take ore to the [[Copperton, Utah|Copperton]] [[Copper concentrator|concentrator]] and [[Froth flotation|flotation]] plant. The longest [[conveyor]] is {{convert|3|mi|km}} long.<ref name="teacher-resources">{{cite web|url=http://www.kennecott.com/library/media/Teacher%20Resources.pdf|title=National Energy Foundation's Out of The Rock|format=PDF (2.1MB)|page=22|publisher=Rio Tinto|accessdate=May 6, 2010|archive-url=https://web.archive.org/web/20101124183157/http://kennecott.com/library/media/Teacher%20Resources.pdf|archive-date=November 24, 2010|url-status=dead}}</ref> |
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As of 2010, Kennecott Utah Copper was the second largest copper producer in the US, and provided about 13-18% percent of the U.S.'s copper needs.<ref name="utah.com-kennecott">{{cite web|url=http://www.utah.com/attractions/kennecott.htm|title=Kennecott Utah Copper's Bingham Canyon Mine|publisher=Utah.com|accessdate=July 11, 2010}}</ref><ref name="infomine">{{cite web|url=http://www.infomine.com/minesite/minesite.asp?site=bingham|title=Bingham Canyon|publisher=Global InfoMine|accessdate=July 11, 2010}}</ref> It is one of the top producing copper mines in the world with production at more than <!-- {{convert|18700000|ST|LT t|sigfig=3|disp=or}} --> 18.7 million short tons (16.7 million long tons; 17.0 Mt). Every year, Kennecott produces approximately <!-- {{convert|300000|ST|t LT|sigfig=3|disp=or}} --> 300 thousand short tons (272 kt or 268 thousand long tons) of copper, along with <!-- {{convert|400,000|ozt|ST LT|sigfig=3|lk=in} --> 400 thousand [[troy ounce]]s <!-- {{convert|13.7|ST|t LT|sigfig=3|disp=or}} --> (13.7 short tons 12.4 tonnes, or 12.2 long tons) of gold, <!-- {{convert|4,000,000|ozt|ST LT|sigfig=4|lk=in}} {{convert|4,000,000|ozt|t|sigfig=4|lk=in}} --> 4 million troy ounces (124 tonnes, 137 short tons or 122 long tons) of silver, about 10 thousand short tons (9,100 tonnes or 8,900 long tons) of molybdenum,<ref name="utah.com-kennecott"/> and about a million short tons (910 kt or 890 thousand long tons) of sulfuric acid, a by-product of the smelting process.<ref name="rock and gem"/> [[Rio Tinto Group|Rio Tinto]] purchased Kennecott Utah Copper in 1989 and has invested about $2 billion in the modernization of KUC's operations. |
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The current mine plan will expire in 2019. Rio Tinto has been studying a plan to extend the open pit {{convert|1,000|ft|0}} southward, which would extend the life of the mine into the mid-2030s. The plan has been contingent on approval by the Rio Tinto board of directors and approximately 25 required environmental permits.<ref>"Bingham Canyon extension could extend life of mine to mid-2030s by moving south wall," ''Mining Engineering'', October 2010, p.10.</ref> |
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===Production=== |
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Bingham Canyon has proven to be one of the world's most productive mines. As of 2004, its ore yielded more than 17 million tons (15.4 Mt) of copper, 23 million ounces (715 t) of gold, 190 million ounces (5,900 t) of [[silver]], and 850 million pounds (386 kt) of [[molybdenum]]. The value of the resources extracted from the Bingham Canyon Mine is greater than the [[Comstock Lode]], [[Klondike Gold Rush|Klondike]], and [[California gold rush]] mining regions combined. Mines in Chile, [[Indonesia]], [[Arizona]], and [[New Mexico]] now{{when|date=May 2014}} exceed Bingham Canyon's annual production rate. High [[molybdenum]] prices in 2005 made the molybdenum produced at Bingham Canyon in that year worth more than the copper.<ref>{{ Cite book| last = Bon| first = R.L.|author2=Krahulec, K.A.| title = Utah, Mining Engineering| date = May 2006| page = 117}}</ref> The value of metals produced in 2006 at Bingham Canyon was US$1.8 billion.<ref>{{ Cite book| last = Bon| first = R.L.|author2=Krahulec, K.A.| title = Utah, Mining Engineering| date = May 2007| page = 120}}</ref> |
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==Environmental impact== |
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In 1990, homes that had been built on former flood plains were discovered to be contaminated with high levels of lead and arsenic.<ref name=epa>{{cite web|title=Kennecott South Zone / Bingham|url=http://www2.epa.gov/region8/kennecott-south-zone-bingham|publisher=EPA|accessdate=May 8, 2014}}</ref> Activities to clean up 100 years of accumulated impacts began in the 1990s, under state [[Utah Department of Environmental Quality]] and federal oversight and are ongoing.<ref name=Butler>{{cite news|last=Butler|first=Kaitlin|title=When the copper is gone, our children will get the pit|url=http://www.sltrib.com/sltrib/opinion/57803204-82/copper-mine-future-pit.html.csp|accessdate=May 8, 2014|newspaper=The Salt Lake Tribune|date=April 11, 2014}}</ref> |
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The EPA lists "Kennecott South Zone/Bingham" on its [[superfund]] webpage, after it was proposed to be listed as a [[superfund site]] in 1994. The South Zone includes the Bingham Mining District in the [[Oquirrh Mountains]], about {{cvt|25|mi||}} southwest of Salt Lake City, the open pit, waste rock dumps, Copperton Mill and other historic sites. The company avoided regulatory issues of being on the NPL by voluntarily cleaning up the contaminated lands, the [[Superfund Alternative Approach]]. The listing proposal was withdrawn in 2008.<ref name=epasouth>{{cite web|title=EPA withdraws proposal to list Kennecott South Zone as Superfund site|url=https://yosemite.epa.gov/opa/admpress.nsf/20ed1dfa1751192c8525735900400c30/223c73bd87a1d380852574b90055738d!opendocument|work=Region 8 superfund|publisher=EPA|date=September 3, 2008|accessdate=May 8, 2014}}</ref><ref>[https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0800601 EPA Superfund Program: Kennecott South Zone, Copperton, UT] EPA, April 26, 2016</ref> More than 25 million tons of mining wastes have been removed; sludge with elevated sulfate concentrations was consolidated and capped on site.{{citation needed|date=May 2014}} |
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===1900–1909=== |
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By 1904, there were three large copper [[smelter]]s and one lead smelter in the Salt Lake valley. The [[sulfur dioxide]] gas emissions from the smokestacks caused significant crop damage to neighboring crops. During the 1904–1905 winter, the farmers gathered together and decided to file suit against the smelters in the United States District Court of Utah.<ref>{{cite journal|last1=Arrington and Gary B. Hansen|first1=Leonard J.|title=The richest hole on earth: a history of the Bingham copper mine.|journal=Utah State Univ Pr|date=1963|volume=11|issue=1|url=http://garybhansen.com/pdfs/misc/rchsthole.pdf}}</ref> In 1906, [[United States federal courts|Federal Court]] Judge Marshall ruled that the smelters could not smelt ores containing more than 10% sulfur,<ref>{{cite news|title=United States Investor|work=Volume 17, Part 2|issue=27-52}}</ref> effectively closing all of the aforementioned smelters. |
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[[File:Panorama of Bingham Canyon Mine in 1907.png|thumb|650px|center|Panorama of the mines of the ''[[Kennecott Utah Copper|Utah Copper Company]]'' and the ''Boston Consolidated Mining Company'' in 1907.]] |
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===1910–1979=== |
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Kennecott Copper Mines was formed in 1910 after a merger of Utah Copper and Kennecott copper mining companies.<ref name="green game">{{cite book|last1=Richards|first1=Deanna J.|title=The Industrial Green Game:: Implications for Environmental Design and Management.|date=1997|publisher=National Academies Press}}</ref> By 1912, environmental protection organizations were complaining about high levels of [[asbestos]] being used in the organization. [[Kennecott Corporation]] was using [[asbestos]] for preventing fires since copper processing requires very high temperatures.<ref name="Asbestos">{{cite book|last1=Miller and Scott Spoolman|first1=George|title=Living in the environment: principles, connections, and solutions.|date=2011|publisher=Cengage Learning}}</ref> Copper has a very high boiling point and also requires use of other chemicals to separate it from other metals and impurities present in the ore. [[Asbestos]] has microscopic particles that dispersed into the atmosphere and contributed to illnesses among workers and individuals living near the mines. [[Asbestos]] is responsible for illnesses such as pleural fibrosis, skin warts and [[lung cancer]].<ref name="Asbestos"/><ref>{{cite journal|title=Miglietta v. Kennecott Copper Corporation.|journal=Appellate Division of Supreme Court of the State of New York.|date=1966|volume=25 A.D.2d 57, 266 N.Y.S.2d 936|url=http://www.leagle.com/decision/19668225AD2d57_169.xml/MIGLIETTA%20v.%20NNECOTT%20COPPER%20CORP|accessdate=June 10, 2014}}</ref> |
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[[Kennecott Corporation]] was also cited as contributing to emissions of heavy metals such as [[arsenic]] and [[mercury (element)|mercury]].<ref>{{cite book|last1=Frosch & Gallopoulos, N|first1=Robert|title="Towards an industrial ecology." The treatment and handling of wastes|date=1992|publisher=Chapman & Hall.|pages=269–292}}</ref> By 1940, [[arsenic]] and [[mercury (element)|mercury]] were also some of the concerns that were raised by environmental protection agencies against [[Kennecott Corporation]].<ref>{{cite journal|last1=Eppinger|first1=Robert|title=Environmental Geochemical studies of selected Mineral Deposits|journal=US Geological survey professional paper.|date=2000}}</ref> Both [[mercury (element)|mercury]] and [[arsenic]] are dangerous to health in large quantities.<ref name="green game"/><ref>{{cite web|title=Kennecott Copper Mine|url=http://www.mesothelioma.com/asbestos-exposure/jobsites/aluminum-plants/kennecott-copper-mine.htm|website=he Mesothelioma Cancer Alliance at Mesothelioma.com|publisher=he Mesothelioma Cancer Alliance at Mesothelioma.com|accessdate=June 23, 2014}}</ref> |
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===1980–1989=== |
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{| class="wikitable" style="margin: 1em auto 1em auto;" |
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|+ '''Chemical spills, 1980-1989''' |
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! scope="col" | Year |
|||
! scope="col" | Amount |
|||
! scope="col" | Substance Released |
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! scope="col" | Cause |
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|- |
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| 1989 || 100,000,000 gal (est) || Process water containing [[arsenic]]|| Unknown<ref name="ROD">{{cite web|title=EPA Superfund Record of Decision|url=http://www.epa.gov/superfund/sites/rods/fulltext/r0802610.pdf|website=EPA.gov|publisher=EPA|accessdate=June 23, 2014}}</ref> |
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|} |
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Investigations in the 1980s revealed contamination in the [[groundwater]] caused by mining operations the release of hazardous materials. The [[State of Utah]] proceeded with legal action against Kennecott and filed a damage claim against the mine in October 1986, for the loss and destruction of the natural resources, specifically the groundwater.<ref>{{cite web|title=Kennecott Utah Copper Company: Natural Resource Damage Claim and Settlement|url=http://leavitt.li.suu.edu/leavitt/?p=86|website=Southern Utah University; Michael O. Leavitt Center for Politics and Public Service|publisher=Southern Utah University|accessdate=June 23, 2014}}</ref><ref name="Problems">{{cite web|title=Problems with Bingham Canyon Mine|url=http://www.earthworksaction.org/files/publications/FS_Problems_BinghamCanyon_2011_low.pdf|website=Earthworksaction.org|publisher=EARTHWORKS|accessdate=June 23, 2014|archive-url=https://web.archive.org/web/20140926172510/http://www.earthworksaction.org/files/publications/FS_Problems_BinghamCanyon_2011_low.pdf|archive-date=September 26, 2014|url-status=dead}}</ref> |
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There was also a threat due to the [[tailings dam]]. An engineering report in March 1988, gave information that the [[tailings dam]] overshadowing the town of [[Magna, Utah|Magna]] had threat of collapse due to an earthquake and that the billion-ton tailings pond would bury the homes nearby if the tailing pond's embankment failed. The mine responded by proposing various potential strategies including buying up entire subdivisions near the [[tailings pond]], calculating the company's liability if the embankment failed, investing $500 million (or ${{inflation|US|.5|1988|r=1}} billion today) to reinforce the embankment, and colluding with state regulators to keep the engineering report out of the public eye.<ref name="Tribune">{{cite news|last1=Fahys|first1=Judy|title=Special Report: How Kennecott concealed warnings of a possible disaster from the people of Magna|url=http://www.sltrib.com/news/ci_8667373|accessdate=June 23, 2014|agency=Salt Lake Tribune|publisher=Salt Lake Tribune|date=March 24, 2008|archive-url=https://web.archive.org/web/20160303222539/http://www.sltrib.com/news/ci_8667373|archive-date=March 3, 2016|url-status=dead}}</ref> |
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===1990–1999=== |
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{| class="wikitable" style="margin: 1em auto 1em auto;" |
|||
|+ '''Chemical spills, 1990-1999''' |
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! scope="col" | Year |
|||
! scope="col" | Amount |
|||
! scope="col" | Substance Released |
|||
! scope="col" | Cause |
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|- |
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| 1999 || 100,000,000 gal (est) || Process water containing [[arsenic]]|| Unknown<ref name="ROD" /> |
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|- |
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| 1998 || unknown || Acid rock drainage || Clogged pipe |
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|- |
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| 1997 || unknown || Copper sulphate || Clogged outlet valve |
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|- |
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| 1997 || unknown || Process water with pH 2.5-4.0 || Ruptured pipeline |
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|- |
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| 1993 || 45,000 gal || Wastewater || Transfer line rupture |
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|- |
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| 1991 || 30,000 gal || Industrial wastewater || Line break |
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|} |
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Starting in the beginning of 1990s, dust emissions from mining began polluting surrounding areas, caused by an area near the mine where PM10 levels (particulate matter larger than 10 μg/m³) began to rise from 28μg/m³ to 50μg/m³, posing severe health concerns for residents. The first report of PM10 rising was proposed by Schwartz and Dockery in 1992. Then, in 1997, Carter (a professor at [[Brigham Young University]]) put forward that the mine discharge of PM10 has caused lung damage to neighboring residents. |
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In 1995, due to scientific research showing that mining had caused the pollution of [[groundwater]], Utah passed laws to make Kennecott companies pay $37 million (or ${{inflation|US|37|1995|r=0}} million today) to control [[water pollution]]. |
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As a result of mine discharge sewage containing large amounts of [[arsenic]] and [[selenium]] – selenium being particularly toxic to birds, fish and amphibians – about 30% of the fish population were killed in the early 1990s. In 1995 Kennecott, [[EPA]] and the [[State of Utah]] signed an agreement saying that Kennecott will continue to clean up the discharge sewage.<ref>{{cite journal|last1=Archer|first1=Victor E.|title=Air pollution and fatal lung disease in three Utah counties.|journal=Archives of Environmental Health|date=1990|volume=45|issue=6|pages=325–334|url=http://legacy.library.ucsf.edu/documentStore/a/enwiki/w/p/awp93d00/Sawp93d00.pdf|doi=10.1080/00039896.1990.10118751}}</ref> |
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===2000–2014=== |
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From 2000 through 2011 the Bingham Canyon copper mine has had numerous [[chemical spills]].<ref name="track record">{{cite web|title=THE TRACK RECORD OF WATER QUALITY IMPACTS RESULTING FROM PIPELINE SPILLS, TAILINGS FAILURES AND WATER COLLECTION AND TREATMENT FAILURES|url=http://www.patagoniaalliance.org/wp-content/uploads/2013/12/Porphyry_Copper_Mines_Track_Record_-_8-2012-1.pdf|website=www.patagoniaalliance.org/|publisher=EARTHWORKS|accessdate=June 23, 2014}}</ref> |
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{| class="wikitable" style="margin: 1em auto 1em auto;" |
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|+ '''Chemical spills, 2000-2014''' |
|||
! scope="col" | Year |
|||
! scope="col" | Amount |
|||
! scope="col" | Substance Released |
|||
! scope="col" | Cause |
|||
|- |
|||
| 2011 || 145,424 gal || Copper [[tailings]]|| Equipment malfunction |
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|- |
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| 2011 || 100,000-290,000 gal|| Copper [[tailings]] || Unknown |
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|- |
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| 2011 || 160,000 gal || [[Tailings]] || Unknown |
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|- |
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| 2010 || 4,000-5,000 gal || [[Sulfuric acid]] || Unknown |
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|- |
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| 2007 || 1,240,000 gal || Process water containing [[arsenic]] || Cold temperatures |
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|- |
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| 2006 || 270,000 gal || Process water || Pump failure |
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|- |
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| 2006 || 660,000 gal || Process water containing [[arsenic]]|| Cracked pipe |
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|- |
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| 2006 || 1,000,000 gal || Process water || Failed indicator |
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|- |
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| 2004 || 4,000,000 gal || Process water containing [[arsenic]]|| Cracked pipe |
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|- |
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| 2004 || 2,000,000 gal || Process water containing [[arsenic]]|| Ruptured process water line |
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|- |
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| 2004 || 202,000 gal || Process water || Pipeline failure |
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|- |
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| 2003 || 70 tons || Copper concentrate || Unknown |
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|- |
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| 2003 || 10.27 tons || Copper concentrate containing [[arsenic]], [[copper]] and [[lead]] || Pipeline rupture |
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|- |
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| 2003 || 240,681 tons || [[Copper]], [[arsenic]] and [[lead]] || Copper concentrate pipeline rupture |
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|- |
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| 2002 || 5,800 gal || Process water from slag pot|| Plugged drain line |
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|- |
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| 2001 || 19 lbs || [[Arsenic]], [[chromium]] and [[lead]] || Tailings pipeline failure |
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|- |
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| 2000 || 110 tons || Ore slurry || Leak in ore line |
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|- |
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| 2000 || 18,000 tons || [[Sulfuric acid]]|| Flange failure |
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|- |
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|} |
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The [[EPA]] has estimated a {{convert|72|sqmi|adj=on||}} plume of contaminated [[groundwater]] has been created over the course of the mine due to multiple spills and runoff. Long-term effects of the underground water supply contamination may include an increased demand for surface water solutions as the population of the [[Salt Lake Valley|Salt Lake]] valley grows since the county will not be able to tap into the [[groundwater]] supply.<ref name="track record" /> |
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In 2007, Kennecott Utah Copper LLC was considering expanding its land holdings to Rose Canyon Ranch in the southern [[Oquirrh Mountains|Oquirrh mountains]] and Yellow Fork Canyon land in [[Salt Lake County]]. Kennecott claims rights to file a mining claim in accordance with the [[Stock-Raising Homestead Act]] of 1916.<ref>{{cite news|last1=Dethman|first1=Leigh|title=Kennecott eyes land in canyon|url=http://www.deseretnews.com/article/700259997/Kennecott-eyes-land-in-canyon.html?pg=all|accessdate=June 23, 2014|publisher=Deseret News|date=September 19, 2008}}</ref> |
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In 2008, the United States [[United States Fish and Wildlife Service|Department of Interior Fish and Wildlife Service]] sued Kennecott after the release of hazardous substances including [[selenium]], [[copper]], [[arsenic]], [[zinc]], [[lead]], and [[cadmium]]. A federal biologist claimed that these chemicals have caused great damage to the ecosystems and resources that support the migrant bird populations, as well as other fish and wildlife habitats.<ref name="Problems" /> |
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In the northern zone near [[Magna, Utah]], the extensive southern [[tailings]] pond has been collecting the [[tailings]] since the mine first started mining production. Kennecott Utah Copper LLC has requested permission for a Tailings Expansion Project (TEP) to expand the tailings pond impoundment in [[Magna, Utah|Magna]], which is already at 1.8 billion ton capacity,<ref name="Tribune" /> and to expand on {{cvt|721|acre|sqmi km2|1|}} of wetlands south of the [[Great Salt Lake]]. The company has come under scrutiny for the instability of the structure. The [[Salt Lake Tribune]] published a report in 2007 revealing that the company failed to disclose information on possible damages that could occur if the [[tailings]] pond collapsed in the event of a major [[earthquake]]. From 2001 through 2009 there have been six earthquakes ranging from 2.3 to 3.4 in magnitude with an average [[epicenter]] only {{convert|3|mi|spell=in||}} away from [[Magna, Utah|Magna]].<ref>{{cite news|title=Scoping Summary Report: Kennecott Utah Copper LLC Tailings Expansion Project|url=http://www.spk.usace.army.mil/Portals/12/documents/regulatory/eis/KUC-TEP_final-scoping-rpt.pdf|accessdate=June 23, 2014|agency=United States Department of the Army Corps of Engineers|date=August 2011}}</ref> |
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==In popular culture== |
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Bingham Canyon Mine was featured in the 1973 made-for-TV movie ''[[Birds of Prey (1973 film)|Birds of Prey]]'', with protagonist helicopter pilot Harry Walker (played by [[David Janssen]]) piloting his [[MD Helicopters MD 500|Hughes 500]] into the crater to track down three bank robbers and their female hostage in an [[Aérospatiale SA 315B Lama]], which was hiding behind heavy mining machinery. It was also featured prominently in [[The Fundamentals of Caring]]. |
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==See also== |
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*[[Bingham Canyon Reclamation Project]] |
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*[[Chuquicamata]], a similarly sized copper mine in Chile |
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==References== |
==References== |
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{{reflist|30em}} |
{{reflist|30em}} |
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[[Category:Geology museums in New Mexico]] |
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==Further reading== |
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[[Category:Precambrian geology of New Mexico]] |
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*Charles Caldwell Hawley. (September 15, 2014) A Kennecott Story: Three Mines, Four Men, and One Hundred Years, 1887–1997. University of Utah Press, {{ISBN|1607813696}}, 336 pages |
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[[Category:Mines in New Mexico]] |
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[[Category:Pegmatite mines]] |
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==External links== |
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{{commons category|Bingham Canyon Mine}} |
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*[http://www.kennecott.com/ Kennecott's Home Page] |
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*[https://web.archive.org/web/20101124143847/http://kennecott.com/library/media/TeacherGuide.pdf Kennecott Copper Mine. Utah Teacher Guide] |
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*John Hollenhorst [http://www.ksl.com/?nid=148&sid=129927 Kennecott Begins Major Expansion Project], November 17, 2005, ksl.com |
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*[http://www.utahrails.net/bingham/bingham-index.php To Move A Mountain: A History of Mining and Railroads in Bingham Canyon] |
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*[http://www.pbase.com/bobt54/kennecott_mine Photo gallery], {{youtube|TzIat5zhb_k|Video}}<!--official--> |
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*[http://www.utahoutdooractivities.com/kennecott.html Visiting the mine] utahoutdooractivities.com |
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*[https://web.archive.org/web/20130601100229/http://www.3d-exposure.com/panos1/copper-mine-1.html Panoramic View of the Bingham Canyon Mine] 3d-exposure.com |
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*[http://www.ksl.com/index.php?nid=460&sid=24748916&page=1#1 Photos of the 2013 landslide] ksl.com |
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*{{HAER |survey=UT-21 |id=ut0029 |title=Utah Copper Company, Bingham Canyon Mine, State Route 48, Copperton, Salt Lake County, UT |photos=26 |color=|dwgs=4|data= |cap=2}} |
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{{Registered Historic Places}} |
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[[Category:1906 establishments in Utah]] |
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[[Category:Buildings and structures in Salt Lake County, Utah]] |
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[[Category:Copper mines in the United States]] |
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[[Category:Geography of Salt Lake County, Utah]] |
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[[Category:Geology of Utah]] |
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[[Category:Historic American Engineering Record in Utah]] |
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[[Category:Industrial buildings and structures on the National Register of Historic Places in Utah]] |
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[[Category:Landslides in the United States]] |
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[[Category:Mines in Utah]] |
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[[Category:National Historic Landmarks in Utah]] |
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[[Category:Rio Tinto subsidiaries]] |
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[[Category:Surface mines in the United States]] |
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[[Category:Tailings dams]] |
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[[Category:Tourist attractions in Utah]] |
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[[Category:Landslides in 2013]] |
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[[Category:National Register of Historic Places in Salt Lake County, Utah]] |
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Latest revision as of 20:45, 31 October 2024
 The Harding Pegmatite Mine is a former beryl quarry in New Mexico. | |
| Location | |
|---|---|
  Harding Mine | |
| Location | Picuris Mountains |
| State | New Mexico |
| Country | United States |
| Coordinates | 36°11′34″N 105°47′41″W / 36.1928°N 105.7946°W |
| Production | |
| Products | Beryl, lithium, tantalum |
| Type | Adit mine |
| History | |
| Discovered | 1918 |
| Opened | 1906 |
| Closed | 1958 |
| Owner | |
| Company | University of New Mexico |
| Year of acquisition | 1979[1] |
The Harding Pegmatite Mine is a former adit mine that extracted lithium, tantalum, and beryllium from a Precambrian pegmatite sill. It ceased operations in 1958 and its owner, Arthur Montgomery, donated it to the University of New Mexico, which runs the site as an outdoor geology laboratory with mineral collecting permitted on a small scale.[2][1]
History
[edit]Although the quartz pegmatite had attracted the attention of prospectors since before 1900, the extensive deposits of lepidolite were not recognized until 1918 by Joseph J. Peyer. Peyer and his partners mined the ore body with explosives, sorted the ore by hand, and hauled the ore to Embudo by wagon, where the nearest rail line was located. At that time, the chief use of lithium was in specialty glass. However, the ore was contaminated with unrecognized tantalite which caused serious difficulties with its use, and production ceased in 1924.
That same year, the Embudo Mining Company was organized by J.L. Danziger and began construction of a mill near Embudo. This was completed and mining resumed in 1927. The main ore body was mined out in 1929 and the mine closed again in 1930. About 3,500 tons of ore were produced with a value of about $140,000. This represented a modest profit over the three years of mill operations but a net loss for the entire period of mining.
High demand for tantalum in 1942 for wartime production, and reports going back to 1931 of microlite at the Harding Mine, led Arthur Montgomery to investigate the old workings. He found considerable rich material in the mine dumps and at the east end of the workings, and he obtained a lease purchase contract on the mine property. With a team of six local miners, ore was extracted with chisels and sorted by hand. Concentration of the small but rich quantity of highly valuable ore was problematic, but the U.S. Bureau of Mines Testing Laboratory in Rolla, Missouri, used an experimental gravity separation method to process 33.5 tons of ore and extracted 6137 pounds of 77.55% niobium-tantalum oxide. This was the largest unit of U.S. tantalum production ever recorded. However, a small mill built at Rinconada failed to meet its rated capacity of 12 tons per day.
Lithium ores were also mined during this period, and by the time mining paused in 1947, the mine had yielded 41 tons of high-grade spodumene, 558 tons of lepidolite ore, nearly 500 pounds of placer tantalite-columbite containing an average of 43% tantalum oxide, and 22,116 pounds of microlite concentrates containing an average of 68% tantalum oxide and 7% niobium oxide. The operations were profitable enough to allow Montgomery to purchase the property outright.
During 1943, the U.S. Bureau of Mines drilled 39 exploratory cores south of the main workings. The cores showed enough content of spodumene and tantalum-niobium minerals to be classified as milling-grade ore. This made the Harding the first U.S. pegmatite mine to have blocked-out reserves. These are still in place and could conceivably be mined in the future.
Beryl had been recognized as a minor accessory mineral at the mine from its inception. However, this was so easily confused with the abundant albite and quartz of the pegmatite that it was not until 1942 that the U.S. Geological Survey recognized that beryl was abundant at the mine. In 1944 Montgomery found a single block of beryl weighing almost 100 pounds at one of the dumps, then uncovered a lens of beryl at the west end of the workings. This produced 23 tons of ore containing 11% beryllium oxide. However, full-scale beryllium mining did not begin until 1950. Ore production reached a ton per day, in spite of the difficulties of hand sorting the beryl from the nearly indistinguishable feldspar and quartz gangue.
In 1950 and 1951, beryl production exceeded 150 tons, making New Mexico the leading beryl-producing state. Production averaged 100 tons per year until 1950, when the death of Montgomery's partner, Flaudio Griego, ended mining operations. Operations were simple, using a crew of four men to mine and hand sort the ore, which was taken out on "Beryl", the mine's mule. Production totaled 690 tons of high-grade ore with 11.2% beryllium oxide and 184 tons of lower-grade ore with 5.5% beryllium oxide, as well as small production of lepidolite.[2]
Geology
[edit]The Harding pegmatite intrudes along the boundary between the amphibolite and schist facies of the Vadito Group.[2][3] The various outcroppings form a belt about 2500 feet long and 150 to 500 feet wide. Radiometric ages are somewhat discordant, ranging from 1260 Mya for four Harding muscovites to 1350 Mya for a Harding lepidolite. A more recent "average age" is given as 1336 Mya, and discrepancies may be due to contamination from the host rock.[1] However, the pegmatite is thought to be up to 100 million years younger than any nearby granite plutons and does not seem to be genetically associated with any of them.
The main mine workings are exposed over a length of about 1100 feet and a breadth of up to 250 feet. The pegmatite is zoned subhorizontally into the following zones:
- At the upper contact with the Vadito amphibolite facies: A white border rind, 1 to 2 inches thick, of fine-grained quartz-albite muscovite pegmatite.
- A continuous layer, typically 1 to 5 feet thick but up to 14 feet thick, of very coarse quartz, albite, and muscovite. This zone also contains microcline, and has abundant accessory apatite, beryl, and tantalite. Beryl is occasionally very coarse and abundant.
- A continuous layer of massive quartz, typically 2 to 8 feet in thickness, but up to 20 to 35 feet. This zone is also rich in muscovite, microcline, and cleavelandite.
- A spectacular quartz and lath-spodumene zone. This zone is typically 6 to 20 feet thick but locally fills the entire interior of the dike to a thickness of 20 to 40 feet. The spodumene occurs as blade-like crystals, sometimes of enormous size, mostly oriented at random but sometimes arranged to form a comb-like structure. Accessory minerals are beryl, apatite, microcline, and tantalum-niobium minerals, especially in the lower part of this zone. There is some pseudomorphic replacement of spodumene by rose muscovite and quartz by cleavelandite.
- The core of the dike, known as "spotted rock", which is relatively fine-grained spodumene, microcline, and quartz, with accompanying finer-grained albite, lithium-bearing muscovite, lepidolite, microlite, and tantalite. Much of the spodumene and microcline have been extensively corroded and replaced by fine-grained micas.
These zones are mirrored at the base of the pegmatite, except that the lower zones tend to be poorer in beryl and more aplitic than pegmatitic. The abundant fine-grained albite is sugary in appearance.
Additional accessory minerals, of no economic importance but of interest to mineral collectors, include almandine, spessartine, and pyrochlore.[2]
-
Massive quartz pegmatite -
Lithium muscovite -
Unusual piemontite-zoisite -
Cleavelandite -
Apatite
Geochemical analysis and analysis of fluid inclusions suggests the pegmatite was injected at temperatures near 600 °C at a depth of 6.0 to 7.5 km (2.0 to 2.5 kbar). The primary zones crystallized under closed-system conditions a temperature of 525 to 425 °C. A separate immiscible CO2-H2O volatile-rich fluid was present in the pegmatite system during crystallization of the primary pegmatite zones. The sugary albite zone formed from a residual Na-rich magma as a response to late-stage pressure release. Saline brines caused lepidolite replacement at temperatures near 265 °C. Finally, small pockets of quartz, feldspar and microlite were crystallized.
Ownership
[edit]In 1974, Arthur Montgomery offered to donate the property to the University of New Mexico. The university leased the property for four years while making numerous improvements, which include a walking tour of the mine. Because the mine property included both patented and unpatented claims, transfer of the title required an act of Congress (Senate Bill 1403). The United States retains the right to mine strategic minerals should it become necessary for the security of the United States.
Persons wishing to visit the mine must contact the chairman, Department of Geology, University of New Mexico, 87131 to obtain permission (which is almost always granted) and release forms.[1]
References
[edit]- ^ a b c d Brookins, Douglas G.; Chakoumakos, Bryan C.; Cook, Clarence W.; Ewing, Rodney C.; Landis, Gary P.; Register, Marcia E. (1979). "THE HARDING PEGMATITE: SUMMARY OF RECENT RESEARCH" (PDF). New Mexico Geological Society Field Conference Series. 30: 127. Retrieved April 16, 2020.
- ^ a b c d Jahns, Richard H.; Ewing, Rodney C. (1976). "The Harding Mine Taos County New Mexico" (PDF). New Mexico Geological Society Field Conference Series. 27: 263.
- ^ Jones, James V. III; Daniel, Christopher G.; Frei, Dirk; Thrane, Kristine (2011). "Revised regional correlations and tectonic implications of Paleoproterozoic and Mesoproterozoic metasedimentary rocks in northern New Mexico, USA: New findings from detrital zircon studies of the Hondo Group, Vadito Group, and Marqueñas Formation". Geosphere. 7 (4): 974–991. doi:10.1130/GES00614.1. Retrieved April 15, 2020.