Calcite crystals darkened by sulfide inclusions. From Vulcan Materials Quarry in Racine, Wisconsin. UW–Madison Geology Museum specimen. (Photo by Pete Rodewald.)



Calcite sceptor crystals from Shullsburg, Wisconsin. UW–River Falls specimen. Sample is about 8 cm high. (Photo by Pete Rodewald.)

Calcite is an abundant mineral found in many geological environments. It forms by precipitation from ground and surface waters, forming the major component of marls and limestone in the ocean, lakes and rivers. It also forms speleothemes in caves, euhedral crystals in vugs, and tufa where springs emerge on the surface. It is the major component of marbles, which forms by the metamorphism of limestones and other carbonate-rich rocks. Calcite also is commonly found in hydrothermal veins. It may occur as a rare accessory in syenitic or pegmatitic igneous rocks. Space allows only a few of the most remarkable calcite occurrences to be mentioned here. Most of the state’s calcite occurrences are in a region underlain by Paleozoic carbonate rocks, which extend in a wide curving band across the state from St. Croix County in the west, south along the Mississippi Valley east to Madison, then north to Green Bay and the Door Peninsula.

Calcite sceptor crystals from Shullsburg, Wisconsin. UW–River Falls specimen. Sample is about 20 cm high. (Photo by Pete Rodewald.)

ASHLAND COUNTY: Granular, sparry calcite is a major constituent of the Bad River marble found throughout the Penokee Range. Here it is associated with dolomite, chlorite, quartz, sericite, tremolite and pyrite. Some outcrops include SE NW sec. 24, T44N R4W and in Penokee Gap along the Bad Rive at SE NW sec. 14 T44N R3W (Van Hise and Irving, 1892).

BAYFIELD COUNTY: Granular, sparry calcite is a major constituent of the Bad River marble found throughout the Penokee Range. Here it is associated with dolomite, chlorite, quartz, sericite, tremolite and pyrite. It is well exposed in the Grandview marble quarry NW NW NW sec. 22 T44N R5W. (Mudrey, 1979) and near the Marengo River in SE sec. 15 T44N R5W (Van Hise and Irving, 1892).

Rhombohedral calcite crystals, from Hazel Green, Wisconsin. Field of view is about 25 cm. UW–River Falls specimen.

BUFFALO COUNTY: Calcite is found as small crystals and cleavable masses in vugs in the dolostones of the Prairie du Chien group. It is associated with drusy dolomite and quartz crystals and pyrite and marcasite now replaced by goethite. Calcite can also be found as travertine in small caves. The travertine commonly fluoresces and phosphoresces a pale blue. Some localities include:
—quarries near Cochrane in the SE SE sec. 3 T.20N. R.12W. and NW NW sec. 24 T22N R.12W. (WSC Field Notes).
—a quarry on County M north of Bluff Siding in the SE NW sec. 30 T19N R10W. Here the calcite exist as two separate generations: an early beige calcite and a later white calcite (WSC Field Notes).

CLARK COUNTY: Calcite occurs as veinlets in schist in the Long Branch Quarry, west of Thorpe. It fluoresces red under shortwave ultraviolet light (Tom Buchholz, pers. com.)

DANE COUNTY: Calcite occurs as crystals in vugs in Prairie du Chien Group dolostones in “extensive quarries just west of Madison”. The crystals are described as yellowish rhombohedrons 3 – 4 mm in diameter (Hobbs, 1895).
—Calcite occurs in crystals in vugs in the Stiennon Quarry, NW SE SE sec. 27 T.7N. R.^E., on the north side of County J near Blue Mounds.
—Tiny white rhombohedral crystals occur in a quarry on County I about 4 miles NE of Nelson in the NW sec. 35 T22N R13W. (W.S.C. field notes, 1992).

DODGE COUNTY: Calcite crystals with sphalerite, galena and dolomite occurs in a small quarry in the Galena Formation at Emmet, 2 miles north of Watertown (Chamberlain, 1877).
—Calcite is a minor component of the Neda iron ore, forming parts of nodules, oolites and the matrix (Hawley and Beavans, 1934).
—Calcite occurs in excellent crystals from a quarry near Mayville at the edge of the Horicon Marsh (Sec. T.11N. R17E.) (LaBerge, 1997, pers. comm.)

DOOR COUNTY: A meter thick bed in the Burnt Bluff Formation contains vugs lined with calcite crystals at Potawatomi Point, Rock Island (Shrock,1940).
—Calcite crystals associated with pyrite, dolomite and bitumen are exposed along the beach at low water along the Lake Michigan shore 2 miles north of Whitefish Bay (Nelson and Roberts, 1963).
—Calcite as clear complex rhombohedral xls. is found in vugs in dolostone with fluorite in an active quarry near Sturgeon Bay.(Gene LaBerge, 1997 pers. communication.)
—Calcite occurs as complex rhombohedrons with fluorite in an active quarry in Sturgeon Bay. (Carl Cochrane, 1999 pers. com.)

DOUGLAS COUNTY: Calcite is found in veins and amygdules in the Keweenawan volcanic rocks throughout the county.
—Calcite occurs in a vein 5 cm across with epidote and native copper in the SW sec. 6 T44N R13W (Irving, 1883).
—Calcite occurs in veins and amygdules in basalt in outcrop in NW SE sec. 2 T44N R13W (Irving, 1883).
—Calcite is found in veins with copper, epidote, prehnite, laumontite at the Percival copper prospect in the N1/2 SW NE sec. 27 T48N R10W, northeast of Blueberry (Grant, 1901).
—Coarse white cleavable calcite intergrown with copper and prehnite is found in Pattison State Park, SW sec. 14 and SE sec. 15 T47N R14W (Grant, 1901).
—Calcite occurs in amygdules in prehnite, quartz, epidote, K feldspar and other minerals at the South Range Quarry, NE NE sec. 1 T47N R12W (Cordua, 1990).

FOND DU LAC COUNTY: Cavities with calcite and pyrite crystals were found in thick-bedded Galena Formation at Moore’s quarry in the west part of Fond du Lac (Chamberlain, 1877).
—Calcite occurs in limestone and as tiny crystals in vugas and on joint surfaces at the Ripon Lime and Materials Company Quarry, NW sec. 20 T.16N R.14E., just west of Ripon.

FOREST COUNTY: Calcite exists in the country rock as well as in veins at the Crandon massive sulfide deposit 10 km. south of Crandon (Lambe and Rowe, 1989).

GRANT COUNTY: Calcite is widespread in the mines and prospects of the Upper Mississippi Valley zinc-lead district. The calcite of the district is well described by Heyl et al. (1959) who document four successive generations of calcite. Type 1 is cloudy, deeply etched crystals colored white, brown, orange-pink or gray. Type 1 crystals are generally steep rhombohedrons modified by {0001} or scalenohedra modified by rhombohedrons. Type 2 calcite is cloudy white to yellow steep scalenohedral xls.. Type 3 calcite forms clear colorless scalenohedra modified by rhombohedrons. Type 4 forms clear highly modified rhombohedrons. The various types form phantoms, scepters or other overgrowths. Parallel growths of complex rhombohedrons are also found. Inclusions, often of marcasite and pyrite, are common. Individual crystals more than a foot long and enormous clusters of great beauty are found in the mines and dumps. Only a few of the many calcite occurrences in the county can be described below. Localities listed for Grant County under galena, sphalerite, marcasite and pyrite are also calcite localities.
—Large crystals with barite, chalcopyrite, galena and sphalerite are found at the Trego Mine in the Platteville district, NW 1/4 sec. 11 T3N R1W (Heyl et al., 1959).
—Spectacular calcite crystals showing parallel growth and scepter crystals with scalenohedra tipped by large rhombohedrons have been found in mines near Livingstone (Raasch, 1924).
—Colorless xls. associated with enargite occur at the Piquette #2 mine in the SW 1/4 NE 1/4 sec. 36 T3N R3W (Heyl, 1964).
—Calcite in the form of tufa or travertine, a recent precipitate deposited around seeps or springs, occur at several spots in Grant County. These include the old “onyx mines” in the SW 1/4 sec. 6 T2N R1W (Heyl, et al., 1959). Nearby is “Tufa Falls” along a tributary to Blockhouse Creek (UW-Platteville, 1988). Travertine also occurs at the center of the S 1/2 sec. 36 T3N R4W (Heyl, et al., 1959). Lastly, another “Tufa Falls” occurs along the Grant River several miles upstream of Burton near Camel Ridge Road along the south edge of sec. 8 T3N R4W (UW-Platteville, 1988).

IOWA COUNTY: Calcite is widespread in the many mines and prospects of the upper Mississippi Valley zinc-lead district in this county. The description of calcite habit under Grant County applies also to Iowa County.
—Hobbs (1895) describes and illustrates excellent calcite crystals from the mines at Linden, Mineral Point and Mifflin. His work details 7 distinct habits. Type 1 are rounded white, brown to pink opaque modified scalenohedra up to 5 cm long. Type 2a are light yellow translucent to transparent unmodified scalenohedra which may form overgrowths on Type 1. Type 2a crystals are corroded and may be up to 15 cm long. Type 2b crystals are essentially unetched and unmodified flat rhombohedra found as 5-10 cm long in geodes. Type 3 are grayish-white, nearly opaque positive scalenohedra. These can form overgrowths on Types 1 and 2a and can be 18 cm long. Type 4 is described as “nailhead spar” consisting of white flat rhombohedrons with scalenohedron modifications. These may be in parallel growths and as scepter crystals on Type 3 crystals. Type 5 crystals form white to greenish white rhombohedron with basal pinacoids. These are usually twinned, with the largest reported twins being 18 cm by 15 cm by 13 cm. Type 6 crystals are steep white opaque rhombohedrons. Many minor modifying forms are also described by Hobbs.
—Strong, (1883) reports “handsome crystals of calcite recently removed measured 5 feet by 2 feet” from a zinc mine in the Linden District. He also remarks on rose-colored massive calcite from this area.
—Taylor (1964) remarks on the abundance of calcite in the mines throughout the Rewey and Mifflin quadrangles.

Manganoan calcite spheres, 7 mm across on drusy quartz with pyrite. From Montreal Mine in Iron County, Wisconsin. (Photo by W. Cordua.)

—Calcite occurs in beautiful crystal specimens from the Montreal and Cary mines in the Gogebic Iron Range. The calcite may be massive, as crested masses or as spherical pink to lavender aggregates of manganoan calcite. The calcite fluoresces a bright red, and is associated with barite, celestine, manganite, hematite and goethite (Dickey, 1936, LaBerge, 1984; Hampel, 1992).
—Calcite occurs with prehnite, laumontite and native copper in the Keweenawan section exposed along the gorge of the Montreal River in sec. 21 T47N R1E (Irving, 1883).

JEFFERSON COUNTY: Small crystals with dolomite, marcasite and sphalerite occur in Galena group sediments in the Havsz Brothers Quarry, sec. 11 T5N R14E near the intersection of US Hwy 12 and County M south of Fort Atkinson (UW-Whitewater, 1980).

JUNEAU COUNTY: Small rhombohedral crystals arte found in vugs in Ordovician dolostone in the Summit Township Quarry, Highway 58, SW sec. 27 T.14N. R.3E. (WSC field notes).

Rhombohedral calcite crystals, from Hazel Green, Wisconsin. Field of view is about 25 cm. UW–River Falls specimen.
LAFAYETTE COUNTY: Calcite is widespread in the many mines and prospects of the Upper Mississippi Valley zinc-lead district, which covers the count, including the subdistricts at Shullsburg and Hazel Green. The description of calcite habits is the same as described for Grant County. Only a few of the many calcite occurrences in the county will be described. Localities for the county under galena, sphalerite, marcasite and pyrite are also calcite localities.
—Good “dogtooth” scalenohedral crystals of calcite occur with galena at the Rickert, Stevens and Company mine NW 1/4 NW 1/4 sec. 14 T1N R2E near Shullsburg (Strong, 1873).
—Large, deep pink “Type 1” calcite occurs at the Liberty Mine, Meeker’s Grove in the NW 1/4 sec. 16 T2N R1E (Heyl, et al., 1959).
—Abundant coarsely crystallized calcite is found in vugs with sphalerite and galena at the New Cottingham Mine, SE 1/4 SE 1/4 NW 1/4 sec. 13 T1N R1E. Similar material occurs nearby at the New Hoskins mine with sphalerite and giant galena crystals in the center of sec. 13 T1N R1E (Heyl, et al., 1959).
—Coarsely crystallized calcite in veins with sphalerite and marcasite occur at the Jug Handle Mine, NW 1/4 NW 1/4 NE 1/4 sec. 14 T1N LR1E (Heyl, et al., 1959).
—Large rhombohedra of calcite were reported from the B.A.T. mine in the SW 1/4 SW 1/4 sec. 18 and NW 1/4 NW 1/4 sec. 19 T1N R2E (Heyl, et al., 1959).
—Calcite occurs in large crystals at the large Calumet and Hecla mine (Eagle-Picher) in sec. 22 T1N R2E near Shullsburg. Crystals in cavities are scalenohedrons over 10 cm long, associated with sphalerite and marcasite (Heyl, et al., 1959).
—Calcite is abundant in large clear crystals at the Rodham Mine, N 1/2 N 1/2 sec. 25 T2NR2E (Heyl, et al., 1959).
—Calcite occurs as water-clear crystals dominated by complex rhombohedrons up to 4 cm across in veins associated with sphalerite and marcasite on the dumps of the New Jersey Zinc Company’s Elmo Mine, NE of Cuba City, east on Hwy 80 (WSC Field Notes).
—Found at the Thompson-Temperley Mine, SW edge of New Diggings (Hosterman, Heyl and Jolly, 1964).
—Abundant at the Teasdale Mine (sec. 21) and the Blackstone Mine (sec. 28) near New Diggings in T1N R1E (Zimmermann, 1969).
—Large calcite crystals with bands of scattered chalcopyrite are associated with barite, galena, sphalerite at the Gritty Six Mine, Meeker’s Grove subdistrict (SW 1/4 sec. 21 T2N R1E (Heyl, et al., 1959).

MANITOWOC COUNTY: Calcite is found as crystals in cavities in brecciated coralline Niagara Formation in sec. 5 T1N R22E, west of Cato (Chamberlain, 1877).
—Calcite and gypsum crystals occur in cavities in Silurian dolostones at Rockwood (Zeitner, 1988).
—Calcite is found in a quarry on Hwy 151 on the north edge of Valders. The calcite forms clear, white to yellow scalenohedra up to 10 cm. long. It is associated with marcasite, sphalerite, fluorite, strontianite and pyrite. (WGNHS Files. Carl Cochrane, 1999, pers. com.).

MARATHON COUNTY: Calcite forms inclusion in quartz and other minerals in the pegmatites of the Wausau pluton, such as is exposed south of Rib Mountain in sec. 19 and 20 T28N R7E (Falster, 1987; Falster et al., 2000).

MILWAUKEE COUNTY: Vugs in “Hamilton Cement Rock” contain calcite crystals over 1 cm long. These occur as colorless to yellowish columnar crystals with scalenohedrons capped by rhombohedrons and as large wine-yellow rhombohedrons (Hobbs, 1895).
—Calcite occurs in “fine” crystals at the Franklin Quarry (Eckert, 1980).
—Colorless translucent crystals showing both positive and negative rhombohedrons is found with millerite in vugs in the Milwaukee Formation at Estabrook Park, sec. 5 T7N R22E. Pyrite, marcasite and sphalerite are associated. The calcite frequently forms the origin for the beautiful radiating millerite clusters found at this locality (Bagowski, 1940).

MONROE COUNTY: Calcite occurs as crystals with dolomite in the Schraufnagel Quarry, near Oakdale.

OUTAGAMIE COUNTY: Calcite occurs as crystals in cavities and fissures in quarries near Kaukauna (Chamberlain, 1877).
—Calcite occurs as small rhombohedral crystals on red drusy quartz in the Brugger Road Quarry, about 14.5 miles south of Bonduel (Carl Cochrane, 1999, pers. com.)

PEPIN COUNTY: Small clear rhombohedral crystals of calcite occur in vugs in dolostone with drusy dolomite and goethite pseudomorphs after both pyrite and marcasite in a quarry north of Stockholm, NW 1/4 NW 1/4 sec. 7 T23N R15W. Calcite also occurs here as travertine crusts up to 5 cm. thick. The calcite normally fluoresces a pale blue. (WSC Field Notes).
—Small white rhombohedral crystals of calcite occur in vugs in dolostone at a quarry on County I about 4 miles northeast of Nelson (NW sec. 35 T.22N. R.13W.) (WSC field notes, 1992).

PIERCE COUNTY: Small calcite crystals showing both positive and negative rhombohedron forms, form xls. up to 5 mm in diameter in a quarry in Prairie du Chien dolostones near Plum City, SE 1/4 SE 1/4 sec. 16 T25N R15W. Associated with minerals are drusy dolomite, drusy quartz and small goethite pseudomorphs after marcasite (WSC Field Notes).
—Travertine and small clusters of steep rhombohedral calcite crystals of white to pale yellow color occur in the Prairie du Chien group dolostones exposed in a quarry on Cady Creek, SE of Spring Valley in the SE 1/4 SW 1/4 SE 1/4 sec. 3 T27N R15W (WSC Field Notes).
—Calcite occurs as travertine and rhombohedral crystals in a quarry south of Elmwood on County P in SE 1/4 SE 1/4 sec. 36 T27N R15W (WSC Field Notes).
—Calcite occurs as complex crystals in a quarry east of Maiden Rock on County S, NW 1/4 sec. 14 T24N R16W. There are 3 generations of calcite: early etched rhombohedrons, later white to yellow rhombohedrons and later powdery to stalactitic calcite. The last 2 generations fluoresce and phosphoresce blue in shortwave and longwave ultraviolet light (WSC Field Notes).
—Calcite occurs as travertine in the Sweeney Quarry quarry west of Spring Valley on 250th Street, SW 1/4 sec. 6 T27N R15W. The calcite fluoresces and phosphoresces blue in shortwave and longwave ultraviolet light (WSC Field Notes).

POLK COUNTY: Calcite occurs in several habits as vein fillings cutting Keweenawan basalt lava flows at the Dresser Trap Rock Quarry, Dresser. The calcite is cream to pale yellow-green and forms flattened crystals with trigonal prism faces and rhombohedron terminations, spherical aggregates of bladed crystals and cleavable masses intergrown with fibrous tremolite along fractures (Cordua, 1989b).
—Calcite occurs as a major component of lake marls, such as is found on the east side of Wolf Lake, NW 1/4 NE 1/4 sec. 13 T36N R19W (WGNHS Files).

RACINE COUNTY: Calcite is found in scalenohedral crystals up to 3 cm long with pyrite in geodic cavities in dolostones on the rapids of the Root River and at Vaughn’s Quarry (Chamberlain, 1877).
—Plates of large scalenohedral calcite crystals, some phantoms formed by pyrite and marcasite inclusions can be found at the Vulcan Materials Quarry (Ives Quarry) north of Racine on Hwy 32. These are associated with marcasite, sphalerite, gypsum and strontianite. (Eckert, 1980; WGNHS files; Scovil, 1994; Gary Richard pers. comm., 1994).

RUSK COUNTY: Calcite occurred sparingly within the carbonate zone at the Flambeau Copper Mine, south of Ladysmith. Calcite occurred as white rhombohedrons, sometimes in groups curved in clusters resembling saddle-shaped dolomite. Some calcite was fluorescent under both shortwave and longwave ultraviolet light. A number of negative casts of scalenohedron shape where found with chalcocite, suggesting calcite may have been more common at an earlier phase of the Flambeau mine’s history but has subsequently been leached away.

SHEBOYGAN COUNTY: Calcite crystals occur in geodiferous Silurian dolostones at Rabie’s Quarry in the N 1/2 sec. 7 T15N R23E (Chamberlain, 1877).

WAUKESHA COUNTY: Calcite-rich marls have been mined by shallow surface pits in the Scuppernong Creek area, such as exposed in the SE 1/4 sec. 34 T6N R17E and the NE 1/4 sec. 3 T5N R17 E (UW-Whitewater, 1982). The marls were deposited in isolated basins in the Kettle Moraine mainly by calcareous algae. These deposits show up on soil survey maps of the region as the Rollins series.

WAUPACA COUNTY: Calcite occurs as small masses in vugs in pegmatite cutting granite in road cuts along County G near Keller Lake., NE of Big Falls. Associated minerals include euxenite-(Y), biotite, fluorite, K feldspar, bastnaesite group minerals, allanite and various sulfides. (Tom Buchholz, 2002, pers. com.)

Calcite and marcasite on dolomite, from the quarry in Oshkosh in Winnebago County, Wisconsin. Specimen is about 8 cm high. Vulcan Materials (Lutz). (Photo by W. Cordua.)

WINNEBAGO COUNTY: Calcite crystals with marcasite in dolomitic limestone and shale is found in the Schultz quarry at Neenah on Tullar road, north of Hwy 114 west of Route 41 (Zeitner, 1988, Carl Cochrane, 1999, pers. com.). (Bagg, 1918) also refers to quarries in the region, citing clear to rose-colored calcite, as well as associated fluorite.
—Attractive calcite, associated with iridescent pyrite, marcasite, sphalerite, galena and other minerals, occurs at the Lutz Quarry south of Oshkosh along Hwy 44 in sec. 29 T18N R16W. (Hobbs, 1905) studied the calcite from this quarry in detail, citing 2 habits: simple unmodified rhombohedral crystals and complex combinations of forms including {0221}, {0112}, {1010}, {2131} and {0112}.
—Calcite is found as crystals in vugs with pyrite, marcasite and rare sphalerite at the Grundy Quarry, in the NE 1/4 NW 1/4 NE 1/4 sec. 33 T19N R1E (UW-Oshkosh, 1989).
—White flat rhombohedra in individuals up to 1 cm across and clusters over 15 cm across on quartz in vugs in Prairie du Chien dolostones at the Allan Quarry NE SW sec. 9 T18N R14E) east of Omro. The calcite xls. fluoresce blue in longwave and shortwave ultraviolet light. (WSC Field Notes, 1993).

WOOD COUNTY: Calcite forms small crystals and masses in quartz veins in the Tork and Haessley Quarries, near Wisconsin Rapids. These fluoresce red in s.w. U.V. light. (Buchholz, 1996).
—Calcite occurs cleavable masses in miarolitic cavities in granite at the Haske Quarry, sec. 25, T24N R2E. (Tom Buchholz et al., 1998).