Sphalerite occurs in a wide range of hydrothermal environments. It is common with chalcopyrite in exhalative massive sulfide bodies associated with volcanic rocks, such as those deposits near Rhinelander and Crandon. It is abundant in low temperature hydrothermal deposited widely known as Mississippi Valley type deposits, such as is found in the southwestern portion of Wisconsin. The deposits in the southwestern part of Wisconsin are internationally known and studied as part of what is called the Upper Mississippi Valley zinc-lead district. The district extends into adjacent Iowa and Illinois (Heyl, et al., 1959). The deposits are dominantly in Ordovician carbonate rocks forming gash veins, replacement bodies, sloping pitches and flats along bedding planes. Gentle but persistent folds, small displacement faults and solution features appear to localize many of the deposits. The mineralogy of the deposits is simple, consisting generally of sphalerite with galena, marcasite, pyrite, barite, calcite and dolomite. The sphalerite readily alters to smithsonite, which forms large deposits in the oxidized zone above the sulfide masses. All of the sphalerite deposits listed below are likely places to find any of the other associated minerals. An excellent detailed description of the district is given by Heyl, et al. (1959).

Sphalerite has been produced from this district since the 1860's. Prior to that, galena and smithsonite were the dominant minerals produced. Hundreds of mines producing sphalerite are known. All of the mines are currently inactive and most are inaccessible or difficult to find because they have been overgrown, collapsed, filled-in or leveled. Many of the dumps have been removed for road metal. Still, scattered piles of waste rock persist throughout Grant, Iowa and Lafayette Counties, providing some interesting mineral collecting as well as testimony to the extent and importance of mining in the region.

Common habits of sphalerite found in the zinc-lead district (Heyl, et al., 1959) are large to drusy crystals, replacement masses of surrounding carbonate rocks, and stalactitic masses. Common colors are red-brown to dark brown. Black varieties often bear manganese. Rarer colors of sphalerite noted are red, yellow, grayish blue and deep purple. "Strawberry jack" refers to sphalerite forming rounded masses or impregnations in shale, often forcing aside shale bedding planes. Hobbs (1895) described the crystallography of crystals collected in the district. Crystals found in a vug within an orthoceras fossil were over 1 cm across, twinned on {111} and showed the following forms: {111} {113} {311} {110} {Okl} {hkl}. Sphalerite is often coated with masses and globules of smithsonite. Partial to complete pseudomorphs of smithsonite after sphalerite are widespread. Heyl, et al. (1959) suggest that the sphalerite may be intergrown with and pseudomorphous after wurtzite. Some sphalerite is found in delicately banded veins featuring gently botryoidal surfaces composed of the tips of small radiating crystals. The bands vary in color from nearly clear through yellowish and reddish brown to nearly black. The crystals are elongated and extend across the composition bands. They are commonly intergrown with marcasite and galena. McLimans, et al. (1980) working with sphalerite from the Shullsburg area correlated the delicate sequence of banding over hundreds of meters within ore bodies and, occasionally, through several kilometers within the district. The writers demonstrated that the light and dark coloration were related to FeS impurities that the earlier sphalerite tended to contain more FeS than later generations.


sphalerite vein in dolostone, Grant County, Wi.

Only a few of the more typical, unusual or important sphalerite occurrences n the state are described below.

COLUMBIA COUNTY: Sphalerite found in mines and at the County K Quarry associated with galena and marcasite in Sec. 22 T.10N. R.12E. near Columbus (Heyl and West, 1982).

DANE COUNTY: Sphalerite is associated with galena in the Platteville Formation at an old mine 1.5 km E of Fitchberg in Sec. 29 T.6N. R.9E. (Heyl and West, 1982).
- Sphalerite is associated with galena in quarries in the Platteville formation near Verona (Heyl and West, 1982).

DODGE COUNTY: Sphalerite was found with galena and calcite in vugs in the Galena Formation in the SE Sec. 20 T.9N. R.15E. near Emmet, north of Watertown (Chamberlain, 1877).

EAU CLAIRE COUNTY: Sphalerite was reportedly found with pyrite, marcasite, chalcopyrite and dolomite from "Eau Claire, WI" (Hobbs, 1905).

FOND DU LAC COUNTY: Sphalerite occurs in masses with pyrite in the Reedstown Member of the St. Peter Sandstone exposed in the Fairwater Quarry SW NE Sec. 36 T15N R13E, SW of Ripon (U.W.-Oshkosh, 1994).

FOREST COUNTY: Sphalerite is a major ore mineral at the Crandon deposit. It is found as grains less than 2 mm across, intergrown with chalcopyrite and pyrite in the massive sulfide zone and, less commonly, in the veins of the stringer zone (May and Schmidt, 1982; Lambe and Rowe, 1989).

GRANT COUNTY: This county is in the heart of the Upper Mississippi Valley zinc-lead district, and as such contains dozens of old mines in which sphalerite occurs. The deposits listed for the county under galena and smithsonite are also sphalerite localities. Calcite, dolomite, marcasite and barite are also found at most, if not all, of these deposits. Only a few of the most important or distinctive localities will be mentioned here.
- Sphalerite is found at the Bridgeport quarry on the north side of Hwy 18 (SW Sec. 20 T6N R5W) where it is associated with galena, pink dolomite, iron sulfides, malachite and celadonite (Heyl & West, 1982).
- Sphalerite was found at a number of mines in the Potosi-Tennyson region including the Wilson Mine, Old Trego Mine, and the Tiffany Mine, all in the SW NW Sec. 36 T.3N. R.3W. (Apell, 1947). Sphalerite is also noted at the Piquette #2 (Heyl, 1964) and the Pleumer level (Heyl, et al., 1959) in the NE 1/4 of this same section.
- Sphalerite was abundant throughout the Platteville subdistrict (Heyl, et al., 1959; Agnew, 1963, Whitlow and West, 1966a) where over 36 mines are known. The mines are dominantly along what was known as the "Blockhouse Range" which extended from the S 1/2 Sec. 26 T.3N. R.1W. to the NE Sec. 36 T.3N. R.2W. and was described by Heyl, et al. (1959), as "a nearly continuous ore body". The main sphalerite ore was generally rosin colored with a range from pale yellow to deep brown. Fine sphalerite crystals are reported from the Rasque mine (NW Sec. 36 T.3N. R.1W.). Other major mines in T.3N. R.1W. are: the Old Blockhouse Mine (S 1/2 SE Sec. 27), the New Blockhouse Mines (SW Sec. 27), the Klar-Piquette Mine (S 1/2 SW Sec. 29), the Graham and Stephens Mines (E 1/2 Sec. 18), the Empire and Enterprise Mines (NE Sec. 15) and the Trego Mine (NW Sec. 11) (Heyl, et al., 1959).
- Pale yellow sphalerite masses with abundant pyrite, marcasite and platy white barite crystals occur at the Beetown Mine, E quarter corner of Sec. 29 T4N R4W (Heyl, et al., 1959).
- Sphalerite is found as pale yellow crystals at the Beloit-Elmo Mine in the Big Patch subdistrict, SE SW Sec. 2 T2N R1W (Heyl, et al., 1959).
- Sphalerite is abundant at the Hazel Green Mine (Sec. 24 T1N R1W) where an ore cave 100' long and up to 20' wide was lined with sphalerite crystals, plus marcasite and galena. Fallen blocks in the cave were crusted over with sphalerite to a thickness of 3" (Bain, 1907). Grant (1905) describes large sphalerite stalactites with cores of marcasite and a yellow to black to yellow internal zoning from the New Deal Mine near Hazel Green. Sphalerite was also common at the Bluebird Mine (NE SE sec. 8 T.1N. R.1W).and the Fairplay Mine (SE sec. 26 T.1N. R.2W.) (Whitlow and West, 1966a).
- Sphalerite with smithsonite, galena, pyrite, marcasite and calcite are found in old mines and pits of the Grab Diggings in SW sec. 19 and NW NW sec. 30 T.4N. R.2W. on both sides of McPherson Branch of the Platte River, west of Ellenboro (West and Blacet, 1971).
- Numerous sphalerite mines occur in the Hurricaine Quadrangle (T.4N. R.4W.) where the sphalerite was associated with smithsonite, pyrite, marcasite, galena, malachite and azurite (west and Heyl, 1985). Some mines refereed to by these authors were the Day's Diggings (SE sec. 15, the Blackjack Mine (NE SE sec. 32),the Beetown Mine (NE sec. 32), and the Yellow Jacket Mine (NE NW sec. 33).
-Sphalerite was mined from small pits where it was found with galena and smithsonite in NE NE sec. 16 T.3N. R.2W. (Whitlow and West, 1966b).
- Sphalerite was mined at the Lafollette Mine, NE NW Sec. 3 T.4N. R.1W (Taylor, 1964).
- Sphalerite occurs at the Washburn Mine, SW SE SE Sec. 34 T.5N. R1W (Taylor, 1964).

IOWA COUNTY: Iowa County is part of the Upper Mississippi Valley zinc-lead district and thus sphalerite is abundant at numerous old mine sites within the county. A number of the mines listed for Iowa County under galena and smithsonite are also sphalerite localities. Usually marcasite, pyrite, barite, calcite and dolomite are associated.
- A number of mines producing sphalerite were located near Mifflin in T5N R1E. These included the Ebenezer Mine (SW SW Sec. 30), the New Dale Rundell (SE NE Sec. 31), the Coker #1 (SE Sec. 30), the Coker #2 (SW Sec. 29), the Coker #3 (SE Sec. 29), the Senator Mine (SW SW Sec. 28), the Penitentiary Mine (NW NE Sec. 34) and the Old Slack Mine (SE SW Sec. 26 T.5N. R.1E.) (Taylor, 1964). Sphalerite is common in drill core from the Defense property in the SE sec. 28 T5N R1E (Lincoln, 1946).
- At least 60 old mines that produced sphalerite are found in the Mineral Point-Linden-Dodgeville subdistrict (Heyl, et al., 1959). These include the Merry Christmas Mine (SW SW Sec. 32 T.5N. R.3E.), the Gilman Mine (just N of center, Sec. 16 T.5N. R.2E.), the Rajah Mine featuring large rosin colored sphalerite crystals (SW SW Sec. 4 T.5N. R.2E.) and the Mason Mine (S 1/2 Sec. 8 T.5N. R.2E.).
- Numerous old mines in the Cobb-Highland region were mined for sphalerite. These include the O.P. David Mine (S 1/2 Sec. 30 T.6N. R.1E.), the Kroll Mine (NW Sec. 5 T.6N. R.1E.) and the Highland Mine (E 1/2 Sec. 28 T.7N. R.1E.) (Heyl, et al., 1959).
- Sphalerite was found at the Eberle Mine, 5 mines north of Cobb (NW NW Sec. 2 T.6N. R.1E. with copper minerals and a complex suite of secondary minerals including smithsonite and aurichalcite (Heyl, et al., 1959).
- Sphalerite was found at the Steppler Farm, 4 miles south of Highland (SE NE Sec. 7 T.6N. R.1E. where it is associated with chalcopyrite and a complex suite of secondary minerals (Heyl, et al., 1959).
- Sphalerite was found in the Demby Weist mines in fissure veins with galena cutting lower Ordovician carbonates and Upper Cambrian sandstones in the NW Sec. 28 and adjacent Sec. 17, 21 and 29 T 7N. R.4E.near Hyde (Heyl and West, 1982).

JEFFERSON COUNTY: Small sphalerite crystals with calcite, pyrite, and marcasite occur in vugs in the Galena Formation in the Hausz Brothers quarry, Sec. 11 T.5N. R.14E. near the intersection of Hwy 12 and County M, south of Fort Atkinson (UW-Whitewater, 1980).


Banded sphalerite, near Hazel Green, Lafayette County, Wi. Sample is about 1 cm. long.

LAFAYETTE COUNTY: Lafayette County is in the heart of the Upper Mississippi Valley zinc-lead district and as such contains numerous sites where sphalerite was mined. Many of the localities listed for this county under galena and smithsonite are also sphalerite localities. Marcasite, pyrite, calcite, barite and dolomite are frequently associated minerals.
- Sphalerite is a major ore at Etna Hill, 3 miles east of Benton (Wheeler, 1908).
- Sphalerite is abundant in the Meeker's Grove subdistrict (T2N R1E) where it is found at over 26 mines (Grant, 1903; Heyl, et al., 1959; Klemic and West, 1964). Some of the major mines are the Big Dick (SW NW Sec. 15) the Connecting Link #1 (E 1/2 SE Sec. 16), the Liberty Mine (NE Sec. 16),the Raisbeck Mine (S 1/2 Sec. 21), and the Trego-Anthony Mine (N 1/2 SE 1/4 Sec. 21).
Sphalerite was extremely abundant in the Hazel Green-Shullsburg subdistrict, in which Heyl, et al. (1959) list 125 mines. The last mine in the district to operate was the Bear Hole Mine near Shullsburg (NE SW sec. 22 T.1N. R.2E.) which closed in 1978. The mill at Shullsburg closed about 1 year later. Some sphalerite, calcite, marcasite and other minerals can still be found on the dump piles.
Most of the mines were in T1N R1E near Benton and New Diggings. These include the Swift and Rooney Mine (SE SE Sec. 10), the old Cottingham Mine with unusual light yellow sphalerite (SW NE Sec. 13), the Hoskins Mine (S 1/2 Sec. 13), the Jug Handle Mine with coarse sphalerite and calcite crystals (NW NE Sec. 13), the Strawberry Blonde Mine (SW SE Sec. 21), the Blackstone Mine (SE NE Sec. 26), the American Zinc Mine (SE Sec. 27), the Fox Mine (SW SW Sec. 21), the Kennedy Mine with its stalactitic sphalerite (SW Sec. 29 ) and the Badger Mine (N 1/2 NE Sec. 30) (Heyl, et al., 1959). Many additional mines were in T1N R2E near Shullsburg. These include the James Mine (SW Sec. 9), the Old Winskell (SW NE Sec. 19), the Calumet and Hecla Mine (Sec. 22), the Blackstone Mine (NW SE Sec. 28) and the Thompson Mine (SE NW and SW NE Sec. 32) (Heyl, et al., 1959). Also in this subdistrict north of Shullsburg in T.2N R.2E are several important mines. These include the Paquette Mine with vugs with unusually large spherical masses of sphalerite (SE SW Sec. 32) and the Rodham Mine (N 1/2 N 1/2 Sec. 25) (Heyl, et al., 1959).
- Sphalerite and galena crystals occur in Silurian dolomite at Belmont Mount (SE NE NE 1/4 Sec. 3 T.3N. R.1E.) (WGNHS outcrop description).

MANITOWOC COUNTY: Sphalerite is found with calcite in a quarry in dolostone on Hwy. 151 at Valders (Wis. Geol. Nat. Hist. Survey Files).

MARATHON COUNTY: Sphalerite occurs as small blackish crystals and masses in quartz from the pegmatites of the Nine Mile pluton (Falster, 1987). such as exposed in the "rotten granite" quarries south of Rib Mt.
- Sphalerite is associated with galena, pyrite, quartz, calcite and chalcopyrite in brecciated volcanic rocks in the center of sec. 7 T.29N. R.7E. An old shaft has been sunk at this site. (LaBerge and Myers, 1983).

MILWAUKEE COUNTY: Sphalerite occur in vugs with millerite, marcasite and calcite in limestones near the Washington Street Bridge at Estabrook Park. The sphalerite crystals are up to 3 cm. in diameter, brown to black in color and frequently twinned. (Bagrowski, 1940). - Sphalerite crystals occur in limestones in Granville Township at Brown Deer. (Chamberlain, 1877).
- Sphalerite crystals occur in rocks along the lake shore at Whitefish Bay (Chamberlain, 1877).

ONEIDA COUNTY: Sphalerite is a major ore mineral in the massive sulfide deposit on the Pelican River east of Rhinelander (Sec. 29 T36N R9E). It is most abundant intergrown with pyrite and chalcopyrite in the lower zone of the ore body (Mudrey, 1979).
- Sphalerite is the most abundant sulfide at the Lynn Deposit with galena, pyrrhotite, pyrite and silver and gold bearing minerals (Kennedy, et al., 1991).

PRICE COUNTY: Sphalerite is a component of the massive sulfide ore at the Ritchie Creek deposit. (DeMatties, 1990).

RACINE COUNTY: Massive, banded to botryoidal sphalerite occurs in vugs in limestone at the Vulcan Materials (Ives) Quarry, Racine. Associated minerals are pyrite, chalcopyrite and large phantom calcite xls. (Scovil, 1994).

ROCK COUNTY: Sphalerite is found associated with galena and marcasite in a quarry and drill core 1.5 km SE of Avon in Sec. 16 T1N R10E (West and Heyl, 1982).

RUSK COUNTY: Sphalerite is a component of the massive sulfide ore at the Flambeau deposit near Ladysmith. The sphalerite tends to be more common toward the footwall portion of the deposit. The sphalerite is intergrown with pyrite and is often banded ranging from dark brown to honey brown in color. some dark brown euhedral sphalerite xls were found in a vuggy carbonate zone, with dolomite, siderite and other sulfides (May, 1977; Rosemeyer, 1995, 1996).
Sphalerite occurs intergrown with pyrite and other sulfides in the Eisenbrey massive sulfide deposit, north of Ladysmith (NW sec. 17 T.35N. R.6W.) (May, 1996).

WAUPACA COUNTY: Sphalerite occurs in road cuts in pegmatite cutting granite 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.)

WINNEBAGO COUNTY: Sphalerite is found in vugs in the Plattevile Formation with galena, marcasite, pyrite, calcite, cerussite and other minerals at the Lutz Quarry in the western portion of Oshkosh on Hwy 44 in T18N R16W (U.S.G.S., 1976).
- Sphalerite is found as crystals in geodes with calcite and pyrite near Menasha (SE sec. 18 T.20N. R.17E.) (Chamberlain, 1877).
- Sphalerite occurs rarely in vugs with calcite at the Grundy Quarry, (NE NW NE sec. 33 T.19N. R.16E). (U.W. Oshkosh, 1989).
Sphalerite occurs as cleavable masses in a breccia cement in the Tullar road quarry, in Neenah. (Carl Cochrane, pers. com.).

WOOD COUNTY: Sphalerite occurs as euhedral crystals in quartz veins in the Tork and Haessley quarries near Wisconsin Rapids. The material fluoresces a pale yellow under s.w. U.V. light. (Buchholz, 1996).
Sphalerite occurs as rare dark gray to black xls, in vugs at the Frederich Schill Quarry, NE of Vesper on the E side of Hwy 180. (Buchholz,1999).
- Sphalerite occurs yellow-brown masses in miarolitic cavities in granite at the Haske Quarry, sec. 25, T24N R2E. (Tom Buchholz, et. al., 1998.).

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