Formula: CuFeS2 with oxidation states Cu1+Fe3+S2-2
Specific gravity: 4.1 to 4.3
Hardness: 3½ to 4
Streak: Greenish black
Colour: Brass yellow, often with an iridescent tarnish
Solubility: Moderately soluble in nitric acid
Common impurities: Ag,Au,In,Tl,Se,Te
Plutonic igneous environments
Chalcopyrite is the most widely occurring copper mineral. It is a
In contact metamorphic environments it may be associated with molybdenite.
In hypothermal (high temperature) and mesothermal (moderate temperature) veins and replacement deposits it occurs associated with galena, sphalerite and dolomite. It may contain gold or silver. Chalcopyrite is often present in large bodies of pyrite. Primary chalcopyrite readily alters to the secondary minerals bornite, covellite and brochantite, and also malachite, azurite, langite and numerous other secondary copper minerals.
The Two Mile and Three Mile deposits, Paddy's River, Paddys River District, Australian Capital Territory, Australia, are skarn deposits at the contact between granodiorite and volcanic rocks. Chalcopyrite is a the main primary copper mineral in the Two Mile deposit, occurring in aggregates and veins with pyrite and magnetite. Chalcopyrite-rich masses up to 70 g containing magnetite, sphalerite, galena and pyrite, have been observed in chloritic skarn. Some chalcopyrite-pyrite masses in hedenbergite skarn contain scheelite enclosed by chalcopyrite (AJM 22.1.36).
At the Mount Kelly deposit, Gunpowder District, Queensland, Australia, the deposit has been mined for oxide and supergene copper ores, predominantly malachite, azurite and chrysocolla. The ores overlie primary zone mineralisation consisting of quartz-dolomite-sulphide veins hosted in dolomite-bearing siltstone and graphitic schist.
Chalcopyrite is the major constituent of the primary ore. It occurs in veinlets associated with pyrite, in carbonate-quartz veins and finely disseminated with pyrite and minor sphalerite in the host siltstone. It also occurs rarely as crystals to 2 mm in quartz veins associated with hematite and partially coated by bornite. Paragenesis for the primary zone is dolomite followed by pyrite, then chalcopyrite and sphalerite, and lastly bornite (AJM 22.1.20 & 25).
At Mount Moliagul, Moliagul, Central Goldfields Shire, Victoria, Australia, chalcopyrite is present as coatings on pyrite crystals in granodiorite and as anhedral masses in quartz veins (AJM 21.1.42).
In Bulgaria pyrite pseudomorphs after chalcopyrite have been found (R&M 95.3.275).
At the Blue Points mine, Thunder Bay, Ontario, Canada, chalcopyrite is associated with galena, and minor pyrite and marcasite (R&M 94.4.319).
At the Thunder Bay Amethyst Mine, Thunder Bay District, Ontario, Canada, chalcopyrite has been found as inclusions in quartz variety amethyst (R&M 94.4.332).
At the Lin Ma Hang mine, North District, New Territories, Hong Kong, China, the lead-zinc deposit is a hydrothermal deposit which lies along a fault zone within altered acid volcanic rocks, consisting mainly of chlorite, biotite, sericite and actinolite, with scattered quartz. (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
The mineralisation consists of a series of fissure vein deposits varying from a few mm to several metres on width. The initial vein filling was coarse milky quartz. this was followed by an intrusion of fine-grained quartz carrying the metallic minerals, galena, pyrite, sphalerite and chalcopyrite, in order of abundance (Geological Society of Hong Kong Newsletter, 9.4.3-27).
Malachite and azurite are occasionally found in close association with chalcopyrite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council).
At Devil's Peak, Sai Kung District, New Territories, Hong Kong, China, the mineralisation occurred in quartz veins in the contact zone between a granite intrusion and acid volcanic rocks. The mine is now closed, and inaccessible for collecting. Chalcopyrite occurred in the quartz veins with beryl, wolframite, molybdenite, pyrite and arsenopyrite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
The Ma On Shan Mine, Ma On Shan, Sha Tin District, New Territories, Hong Kong, China, is an abandoned iron mine, with both underground and open cast workings. The iron ores contain magnetite as the ore mineral and occur predominantly as masses of all sizes enclosed in a large skarn body formed by contact metasomatism of dolomitic limestone at the margins of a granite intrusion. In parts of the underground workings magnetite is also found in marble in contact with the granite. The skarn rocks consist mainly of tremolite, actinolite, diopside and garnet. Malachite and azurite are occasionally found in close association with chalcopyrite, formed by the action of carbonated water on the chalcopyrite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
The Needle Hill Mine, Needle Hill, Sha Tin District, New Territories, Hong Kong, China, is a tungsten mine, abandoned in 1967. The principal ore is wolframite, and the principal gangue mineral is quartz. Molybdenum also occurs. The mineralisation consists of a series of parallel fissure veins that cut through granite. Wolframite and quartz are the main minerals, but galena, sphalerite, pyrite, molybdenite and fluorite have also been found here (Geological Society of Hong Kong Newsletter 9.3.29-40). The quartz-wolframite veins are of high-temperature hydrothermal formation, and grade into wolframite-bearing pegmatites.
Chalcopyrite is sometimes associated with wolframite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
At Chuen Lung, Tsuen Wan District, New Territories, Hong Kong, China, in fissure veins in granite rocks in a small stream near Chuen Lung, silver-bearing galena occurs associated with massive granular amber coloured sphalerite, chalcopyrite, pyrite and pyrrhotite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
The Lin Fa Shan deposit, Tsuen Wan District, New Territories, Hong Kong, China, is located in a remote area of the Tai Mo Shan Country Park, on a steep west facing slope of Lin Fa Shan, just above the abandoned village of Sheung Tong. The surrounding hillsides are covered with shallow excavations, representing past searches for wolframite, the natural ore of tungsten. The abandoned workings are extremely dangerous with unsupported tunnels, open shafts and no maintenance since their closures in 1957; the workings should not be entered (http://industrialhistoryhk.org/lin-shan).
Malachite and azurite are occasionally found in close association with chalcopyrite formed by the action of carbonated waters on the chalcopyrite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council).
At Herrensegen, Schapbach, Schartzwald, Germany, chalcopyrite occurs with covellite (FM 2318).
At Lettermuckoo Quarry, Kinvarra, Connemara, Galway County, Connacht, Ireland, the minerals are hosted by a megacrystic pink to grey monzogranite, with occasional pegmatitic segregations.
Tiny (<1 mm) golden crystals of chalcopyrite occasionally overgrow fluorite and baryte. Rarely, isolated sphenoidal crystals and crystal groups, which may reach several millimetres across, occur (JRS 22.40).
At Guanajuato, Mexico, acanthite-chalcopyrite pseudomorphs after polybasite have been found (KL p124).
At the Mponeng Mine, West Wits, Far West Rand, West Rand District Municipality, Gauteng, South Africa, brass-coloured crystals of chalcopyrite less than 6 mm have been found included in quartz and on baryte, associated with galena and pyrrhotite (R&M 96.4.222).
At the Palabora Mine, Phalaborwa, Mopani District, Limpopo, South Africa, chalcopyrite occurs in a carbonatite (R&M 92.5.436-437).
At Alderley Edge, Cheshire, England, UK, copper mineralised solutions percolated through porous sandstone and deposited barium, cobalt, copper, lead, vanadium and zinc minerals between the sand grains. Anhydrite formed as cement in permeable rocks, then baryte was deposited, followed by pyrite, chalcopyrite, sphalerite and galena. Subsequently a second generation of baryte and iron-rich calcite followed. These minerals crystallised from highly saline, sulphate-rich brines, at a temperature of 50 to 60o C (RES pps 49-50). A specimen of chrysocolla with a pseudomorph of goethite after chalcopyrite has been found (RES p55).
At Redruth, Cornwall, England, UK, chalcopyrite has been found with tetrahedrite and calcite (FM 47545).
At the Clargillhead vein, Garrigill, Alston Moor, Eden, Cumbria, England, UK, chalcopyrite is a common sulphide. In addition to its presence as inclusions in galena, it infills void spaces within radiating quartz and appears to be free of inclusions generally, though rare masses of pyrite and gersdorffite up to 5 microns across were found within it. The chalcopyrite has been found intergrown with galena, or altered to chalcocite and covellite, or to banded limonite, sometimes intergrown with small native silver droplets (JRS 23.49).
At Croft quarry, Blaby, Leicestershire, England, UK, chalcopyrite has been found as inclusions in analcime and also disseminated in the host diorite. Chalcopyrite crystals to 1 mm have also been found associated with fluorite, calcite and analcime (JRS 20.13-14, RES 189).
At Breedon quarry, Breedon on the Hill, Leicestershire, England, UK, chalcopyrite occurs with calcite (RES p202, 208).
At Cloud Hill Quarry, Breedon on the Hill, Leicestershire, England, UK, chalcopyrite occurs with calcite, dolomite and baryte (RES p205)
At Earl Ferrers' mine, Staunton Harold, Leicestershire, England, UK, chalcopyrite occurs with galena, sphalerite, calcite, dolomite and baryte (RES p222, 223).
At Barrasford Quarry, Chollerton, Northumberland, England, UK, a few small patches of chalcopyrite have been found within masses of sphalerite within calcite veins JRS 21.8).
At Wotherton mine, Chirbury, Shropshire, England, UK, chalcopyrite occurs with calcite and pyrite (RES p285).
At the Shadwell quarry, Much Wenlock, Shropshire, England, UK, chalcopyrite occurs with calcite on limestone (RES p296).
At the Pennerley mine, near Worthen, Shropshire, England, UK, chalcopyrite occurs with calcite, quartz and baryte (RES p290).
At the Ecton mine, Staffordshire, England, UK, chalcopyrite occurs with calcite, baryte, pyrite, galena and malachite (RES p302-307).
At Judkins quarry, Nuneaton, Warwickshire, England, UK, chalcopyrite has been found as pseudomorphs after chalcocite, with calcite (RES p324)
At the Magma mine, Pioneer District, Pinal county, Arizona, USA, chalcopyrite crystals have been collected with a purple bornite surface, and also on quartz crystals; crystalline masses of chalcopyrite have been found in association with sphalerite (R&M 95.1.84).
At Joplin, Jasper county, Missouri, USA, tetragonal crystals of chalcopyrite have been found epitaxial on sphalerite (FM 47452).
At the Sweetwater Mine, Ellington, Reynolds county, Missouri, USA, chalcopyrite pseudomorphs after galena have been found (KL p131).
chalcopyrite to goethite
The first stage of copper supergene mineral formation is the oxidation of a primary copper-containing ore mineral, such as chalcopyrite. This is a complex process, but the reaction can be summarised as:
chalcopyrite + oxygen + water → copper ions + sulphate ions + goethite + sulphuric acid
4CuFeS2(s) + 17O2(g) + 6H2O(l) → 4Cu2+(aq) + 4SO42-(aq) + 4FeO(OH)(s) + 4H2SO4(aq)
The copper and sulphate ions are then free to react with carbonate ions in solution to form a range of supergene copper sulphates and carbonates (JRS 18.12).
chalcopyrite to sulphur
Oxidation of pyrite forms ferrous (divalent) sulphate and sulphuric acid:
pyrite + oxygen + water → ferric sulphate + sulphuric acid
FeS2 + 7O + H2O → FeSO4 + H2SO4
The ferrous (divalent) sulphate readily oxidizes to ferric (trivalent) sulphate and ferric hydroxide:
ferrous sulphate + oxygen + water → ferric sulphate + ferric hydroxide
6FeSO4 + 3O + 3H2O → 2Fe2(SO4)3 + 2Fe(OH)3
Ferric sulfate is a strong oxidizing agent; it oxidises chalcopyrite according to the reaction:
chalcopyrite and ferric sulphate to copper sulphate, ferrous sulphate and sulphur
CuFeS2 + 2Fe2(SO4)3 → CuSO4 + 5FeSO4 + 2S
chalcopyrite, arsenopyrite, CO2 and O2 to Fe-tennantite, siderite and sulphur
10CuFeS2 + 4FeAsS + 4CO2 + 8O2 = Cu10Fe2As4S13 + 4Fe(CO3) + 11/2S2
chalcopyrite, arsenopyrite and pyrite to Fe-tennantite and troilite
10CuFeS2 + 4FeAsS + FeS2 = Cu10Fe2As4S13 + 13FeS
chalcopyrite, arsenopyrite and sulphur to Fe-tennantite and pyrite
10CuFeS2 + 4FeAsS + 13/2S2 = Cu10Fe2As4S13 + 12FeS2
This reaction occurs at a comparatively low temperature (CM 28.725-738).
chalcopyrite, arsenopyrite and sulphur to Fe-tennantite and troilite
l0CuFeS2 + 4FeAsS + l/2S2 = Cu10Fe2As4S13 + l2FeS
chalcopyrite and chalcocite to bornite
CuFe3+S2 + 2Cu2S = Cu5FeS4
This reaction occurs in the supergene enrichment zone (JRS 18.14).
chalcopyrite, stibnite and sulphur to Fe-tetrahedrite and pyrite
10 CuFeS2 + 2 Sb2S3 + 3/2 S2 = Cu10Fe2As4S13 + 8FeS2
enargite and pyrite to Fe-tennantite, chalcopyrite and sulphur
4Cu3AsS4 + 4FeS2 = Cu10Fe2As4S13 + 2CuFeS2 + 7/2S2
Fe-tetrahedrite, berthierite and sulphur to chalcopyrite and stibnite
Cu10Fe2Sb4S13 + 2FeSb2S4 + 11/2S2 = 10CuFeS2 + 4Sb2S3
Fe-tetrahedrite, siderite and sulphur to chalcopyrite, stibnite, CO2 and O2
Cu10Fe2Sb4S13 + 8Fe(CO3) + 13/2S2 = 10CuFeS2 + 2Sb2S3 + 8CO2 + 4O2
The diagram below is a Pourbaix diagram for Cu-Fe-S-H2O (IJNM 07(02).9.23). It shows the relationship between copper Cu, chalcopyrite CuFeS2, tenorite CuO, covellite CuS, cuprite Cu2O, chalcocite Cu2S, pyrite FeS2 and hematite Fe2O3.
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