Chalcopyrite from Flambeau Mine, Rusk County, WI. (Photo and specimen by Dan Behnke.)

Formula: CuFeS2 Tetragonal


Chalcopyrite is an important ore of copper found in a wide range of hydrothermal environments. It is often associated with sphalerite and galena. It oxidizes to form copper minerals such as malachite, azurite, cuprite and tenorite. Copper liberated from the breakdown of chalcopyrite may accumulate in secondary supergene enrichment zones, forming chalcocite, bornite, covellite and similar minerals. Most of Wisconsin’s chalcopyrite deposits are in the massive sulfide deposits in middle Precambrian volcanic rocks in the northern portion of the state. Here it is commonly massive and intergrown with pyrite and sphalerite. Chalcopyrite is also found in the southwestern part of the state in the deposits of the Upper Mississippi Valley zinc-lead district. Here it occurs as massive material, euhedral crystals with galena, baryte and sphalerite, and as exsolution blebs within sphalerite and galena (Heyl et al., 1959). Small amounts of chalcopyrite occur in the Keweenawan volcanic rocks in the northwestern part of the state.

ASHLAND COUNTY: Chalcopyrite was found in a calcite vein with pyrite cutting cherty magnetite iron formation encountered in drill core from T.41N. R.1W., west of Butternut, (U.S.G.S., 1976).
— Major component of the copper nickel ore deposits in the N 1/2 Sec. 30 and E 1/2 sec. 21 T.45N. R.4W., near Mineral Lake. Here the chalcopyrite is associated with pyrrhotite, pentlandite and cubanite. (Bakheit, 1981).

BAYFIELD COUNTY: Chalcopyrite is reported with azurite and malachite in old prospect pits in NE NW sec. 2 T.44N. R.6W. , near Drummond (Grant, 1901).
— Chalcopyrite occurs in seams cutting basalt exposed in a small pit in the SE sec. 2 T.43N. R.7W. (Grant, 1901).
— Chalcopyrite with azurite and malachite occurs in the NW NW sec. 6 T.44N. R.5W. north of Namakagon Lake (Dutton, 1971).
— Chalcopyrite occurs with azurite and malachite in a prospect near Upper Eau Claire Lake (NE SE sec. 15 T.44N. R.9W.) (Dutton, 1971).

CLARK COUNTY: Copper sulfides, probably chalcopyrite, occurs as tiny grains n a quartz vein at the Long Branch Quarry west of Thorpe.

CRAWFORD COUNTY: Reported associated with malachite near Soldier’s Grove. (Hobbs, 1905). — With azurite and malachite at the Copper Creek Mine, W 1/2 sec. 26 T.10N. R.5E. 1 km. west of Mt. Sterling (Heyl and West, 1982).
— Found at the Plum Creek Copper Mine, north of Wauzeka, in the SE 1/4 SW 1/4 Sec. 26 T.8N. R.5W. (Heyl et al., 1959).

DOUGLAS COUNTY: Massive chalcopyrite grains up to 0.5 cm. across occur in amygdules with quartz, K feldspar, epidote and chlorite in Keweenawan basalts exposed at a quarry just west of the Parkland Dump on the road to the Flannagan Lookout Tower near South Range (NW NW sec. 1 T.47N. R.13W). (Cordua, 1989).
— Chalcopyrite occurs in veins and amygdules in Keweenawan basalts at the Amnicon copper prospect in the NE NW sec. 11 T.47N. R.13W. It is found here with chalcocite and malachite. (Dutton, 1972).
— Chalcopyrite occurs in the Aster prospect pits in NW sec. 28 and NE sec. 29 T.48N. R.10W. (Dutton, 1972).

EAU CLAIRE COUNTY: Chalcopyrite is described as occurring with pyrite, marcasite, sphalerite and dolomite “from Eau Claire” (Hobbs, 1905).

FLORENCE COUNTY: Reported “just south of Tipler” (Eckert, 1980).

FOREST COUNTY: An important ore mineral at the Crandon deposit, near Little Sand Lake, SE Sec. 25 T.35N. R.12E. It is generally fine-grained to massive material intergrown with and interstitial to sphalerite and pyrite in the massive sulfide zones. Grains range up to 10 mm across. It is also found disseminated in veins with quartz and pyrite in the stringer zone under the massive sulfide. (May and Schmidt, 1982; McCarthy et. al., 1986, Lambe and Rowe, 1989).
— Chalcopyrite occurs as an accessory in quartz veins cutting small pegmatites along State Hwy. 55 south of Alvin. (Tom Buchholz, 2003, pers. commun.)

GRANT COUNTY: Associated with sphalerite and enargite in vugs at the Piquette #2 mine, SW NE Sect. 36 T.3N. R.3W., near the town of Tennyson. (Heyl, 1964).
— Reportedly found with cuprite and malachite from “near Boscobel”. (Hobbs, 1905).
— Found at the Trego Mine in SE NE Sect. 10 and NW Sect. 11 T.3N. R.1W. near Platteville with sphalerite and galena. (Agnew, 1963).
– Found at the Graham and Stephens Mine near Platteville, E 1/2 Sec. 18 T.3N. R.1W. (Heyl et al., 1959).
— Found at the Empire and Enterprise Mines in S 1/2 SE 1/4 NE 1/4 Sec. 15 T.3N. R.1W. near Platteville. (Heyl et al., 1959).

IOWA COUNTY: Chalcopyrite is widespread through this portion of the Upper Mississippi Valley zinc-lead district where it is associated with sphalerite, galena, and numerous secondary copper minerals. (Strong, 1877; Raasche, 1928; Heyl et al., 1959).
— Chalcopyrite is found with sphalerite at the Harris Mine, near Mineral Point at the SW 1/4 SE 1/4 Sec. 32 T.5N. R.3E. (Heyl et al., 1959).
— Chalcopyrite is the major ore mineral found at a group of small copper mines located in T.4N. R.3E. near Mineral Point. These include the Temby Mine in the NE 1/4 Sec. 5, the Beach Mine in the N 1/2 Sec. 4 and the Wasley Mine, N 1/2 SE 1/4 NE 1/4 Sec. 5. In each, the chalcopyrite is altered to tenorite, chalcocite, malachite and azurite and associated with smithsonite, marcasite and limonite (Heyl e. al., 1959).
— Chalcopyrite is found at the Pierson Prospect in the NW Sec. 5 T.4N. R.3E. where it is associated with sphalerite, pyrite, marcasite, galena, chalcocite and covellite (Heyl et al., 1959).
— Found at the Ansley Copper Mine, N 1/2 SE 1/4 Sec. 32 T.5N. R.3E. where it is found with limonite, azurite and malachite in “lumps up to 200 lbs.” in clay. (Heyl et al., 1959).
— Occurs in the mines south of Linden, W 1/2 Sec. 21 T.5N. R.2E. (Heyl et al., 1959).
— Found at the Eberle Mine, 5 miles N. of Cobb at NW 1/4 NW 1/4 Sec. 2 T.6N. R.1E. where it is associated with chalcocite, malachite, azurite, cuprite, aurichalcite, sphalerite and smithsonite (Heyl et al., 1959).
— Found at the Steppler Mine, 4 miles southwest of Highland in SE 1/4 NE 1/4 Sec. 7 T.6N. R.1E. where it is associated with chalcocite, malachite, azurite, chrysocolla, aurichalcite, sphalerite and smithsonite. (Heyl et al., 1959).
— Found at the Otter Creek Copper Mine, Sec. 10 and 15 T.7N. R.2E. on east side of Otter Creek, near Clyde. (Heyl and West, 1982).

LAFAYETTE COUNTY: A minor component of the zinc-lead-copper ore body at the Thompson-Temperley mine, SW edge of New Diggings in Section 27 T.1N. R.1E. (Hosterman, Heyl and Jolly, 1964).
— reported associated with malachite form near Wayne. (Hobbs, 1905). May be same locality by Heyl et. al. (1959) near South Wayne at SE 1/4 SW 1/4 Sect. 8 T.1N. R.5E.
— Found at a small copper prospect south of Ames Branch in the Calamine quadrangle at NE SE Sect. 22 T.2N. R.3E., where it is seen altering to malachite, azurite, cuprite and limonite. (Klemic and West, 1964).
— Found near Gratiot in the SE 1/4 NW 1/4 Sec. 36 T.2N. R.3E. (Heyl et. al., 1959).
— Found with sphalerite and aurichalcite in old dumps in the SE SW sec. 12 T.1N. R.2E. near Leadmine (Heyl et al., 1959).
— Chalcopyrite is found as scattered bands of small xls. in larger calcite xls. associated with barite at the Gritty Six Mine, SW 1/4 Sec. 21 T.2N. R.1E., near Meeker’s Grove. (Heyl et. al., 1959).
— Small chalcopyrite xls. are found at the Baxter Mine NW 1/4 NE 1/4 Sec. 29 T.2N. R.1E. near Meeker’s Grove. (Heyl et al., 1959).

MARATHON COUNTY: Chalcopyrite occurs locally associated with malachite in the greenstone in sec. 33 T.30N. R.6E. (Dutton and Bradley, 1970).
— Chalcopyrite occurs with malachite and pyrite in a roadcut along Hwy N SW sec. 35 T.29N. R.8E. (LaBerge and Myers, 1983).
— Chalcopyrite occurs in vein quartz with pyrite and malachite cutting schist near the “old gold mine shaft” on the east side of the Eau Claire river near Eason (SW sec. 26 T.29N. R.9E.). (LaBerge and Myers, 1983).
— Chalcopyrite occurs with sphalerite, galena, pyrite, quartz and calcite in brecciated volcanic rock in the center of sec. 7 T.29N. R.7E. An old shaft was sunk at this locality (LaBerge and Myers, 1983).
— Chalcopyrite occurs with pyrite, malachite and quartz in sheared gneisses and greenstones in an outcrop in the NW SW SW sec. 9 T.26N. R.7E. (LaBerge and Myers, 1983).
— Chalcopyrite occurs disseminated in metavolcanic rocks in outcrop in Big Sandy Park, sec. 18 T.29N. R.9E. (LaBerge and Myers, 1983).
— Chalcopyrite occurs in calcite veins cutting serpentinite in a roadcut on County A, middle of the north edge of section 34 T.30N. R.6E. (Brown, 1995, pers. com.)

MARINETTE COUNTY: Chalcopyrite occurs with pyrrhotite in the outcrop at Pine Rapids (AKA “LaSalle Falls”) NW SE sec. 30 T.39N. R.18E. (Schulz and LaBerge, 2003).

ONEIDA COUNTY: A major ore mineral in the massive sulfide copper-zinc ore body on the Pelican River east of Rhinelander in Sect. 29 T.36N. R.9E. The mineral is a major component of the lower part of the ore body where it is intergrown with pyrite. It is also found in the footwall stockwork with pyrite, magnetite and pyrrhotite. (Mudrey, 1979).
— Important ore mineral at the Lynn Deposit with galena, sphalerite and gold and silver minerals. (Kennedy et al., 1991).

POLK COUNTY: Found as thin films and coating on joint surfaces in basalt, gabbro and quartz veins in the trap rock quarry at Dresser, sec. 5 and 6 T.33N. R.19W. (Cordua, 1989).

PORTAGE COUNTY: Reported at the old “graphite mine” located 1 mile north of Hwy 10 on County G, north of Junction City. (Rosa Bord, 1990, personal communication).

PRICE COUNTY: Chalcopyrite is abundant in the massive sulfide ore at the Ritchie Creek deposit (DeMatties, 1990).

RACINE COUNTY: Occurs with sphalerite and calcite at the Ives Quarry in Racine. (Gary Richards, 1994, personal communication).

RICHLAND COUNTY: Found associated with chalcocite and malachite as rich ore samples in Prairie du Chien Group rocks found in washes about 5 km west of Richland Center at NE Sec. 25 T.10 N. R.1W. (Heyl and West, 1982).
— Occurs in veins in Cambrian sandstone on the north bank of the Wisconsin River, SE Sec. 35 T.9N. R.1E. near Avoca. (Heyl and West, 1982).

RUSK COUNTY: Common component of the massive sulfide ore body at the Flambeau deposit near Ladysmith. It is especially common toward the hanging wall, when it forms masses interstitial to pyrite up to 5 cm. across. It is also found in veins cross-cutting the massive sulfide zone and as a late generation supergene mineral. These late coatings often occur as botryoidal-like coatings on primary chalcopyrite or as micro-tetragonal crystals on bornite. (May, 1977).
— Chalcopyrite is a major ore mineral in the Eisenbrey massive sulfide body north of Ladysmith (NW sec. 17 T.35N. R. 6W.).It is associated with pyrite, pyrrhotite and sphalerite. (May, 1996).

SAUK COUNTY: Found in small pits with chalcocite, malachite and hematite on the upper east side of Hagerman Hill, Sect. 34 T.13N. R.3E. Hagerman Hill is located south of LaValle. (Heyl and West, 1982).

TAYLOR COUNTY: Chalcopyrite occurs at the Bend massive sulfide deposit NW, sec. 2 T.32N. R.2W. northeast of Gilman. It is associated with pyrite tetrahedrite and gold tellurides. (DeMatties and Rowell, 1991).

VERNON COUNTY: Traces of chalcopyrite occur in the Prairie du Chien rocks at the Swangster Prospect in Sec. 34 T.14N. R.5W. west of Wesby (Heyl and West, 1982). – Chalcopyrite is found in prospects along both sides of Read’s Creek, Sec. 34, 35, 36 T.12N. R.4W., 4-5 km west of Readstown.

WAUPACA COUNTY: Chalcopyrite occurs with other sulfides in a pegmatite exposed in a highway expansion on County G about 1 mile east of Big Falls (Tom Buchholz, 2002, personal communication ).

WOOD COUNTY: Found in veins with fluorite and quartz at the Turner quarry, west of Pittsville. (Crowns, 1976).
— Occurs as masses and occasional acicular xls. in vugs in the granite of the Haske Quarry, (SW SE sec. 25 T.24N. R.2E.). It is also found as small xls. in vugs. (Buchholz et al., 1998)