Fluorite crystals, from Sturgeon Bay in Door County, Wisconsin. Largest crystal is 0.5 cm across. (Photo by W. Cordua)

Formula: CaF2 Isometric


Fluorite crystals, from Sturgeon Bay in Door County, Wisconsin. Field of view is about 4 cm. (Photo by W. Cordua)

Fluorite often forms coarse cleavable masses or cubic crystals. It can take on a range of attractive colors, most often purple. Fluorite occurs in all types of hydrothermal deposits. It also forms as an accessory in igneous rocks, especially syenites and granite pegmatites. In Wisconsin, most fluorite localities are in the Wausau area, associated with the Wausau and Stettin plutons. Fluorite can also be found locally in low temperature veins in limestones and dolostones, where it is associated with calcite and dolomite. Finally, fluorite occurs in Wisconsin as a heavy mineral in Keweenawan sediments (Tyler, 1940).

ASHLAND COUNTY: Fluorite is an accessory in granite intruded into gabbro along the Falls of the Bad River 0.4 km. northwest of Mellin in the E 1/2 Sec. 31 T.45N R.2W (Irving, 1882; Van Alstine, 1976).

Green to purple fluorite fill in a “thunder egg.” From Iron County, Wisconsin. (Photo by Dave and Sue Midkiff.)

DOOR COUNTY: Fluorite as zoned clear, brown to yellow cubic xls in vugs with calcite is found in an abandoned quarry on the south side of Sturgeon Bay. Individual xls. may be several centimeters across. Fluorescent and phosphorescent both shortwave and longwave ultraviolet light (Carl Cochrane, 1998 personal communication).

FLORENCE COUNTY: Fluorite is found locally with pyrrhotite in granite in sec. 7 T.38N R.20E (Dutton and Bradley, 1970).
—Fluorite occurs with quartz in a shear zone cutting the Hoskin Lake Granite at NE NE Sec. 18 T.38N R.20E (Sims et al., 1992).

Fluorite from the Nine Mile Pluton near Wausau in Marathon County, Wisconsin. Scanning electron microscope image. (Photo by Al Falster.)

GREEN LAKE COUNTY: Fluorite occurs as tiny purple crystals on drusy quartz in vuggy dolostone at the Morris Pit.

IOWA COUNTY: Fluorite is found with sphalerite along shear zones and faults at the Grayville Mine in Sec. 31 T.5N R.3E near Mineral Point (Van Alstine, 1976). Fluorite is otherwise rare in the rocks of the Upper Mississippi Valley zinc-lead district.

IRON COUNTY: Green to purple fluorite occurs as a filling in “thunder eggs” in rhyolite from an undisclosed locality in Iron County.

MANITOWOC COUNTY: Fluorite occurs as rare purple vein fillings in the Alders quarry, on Highway 151 on the north edge of Alders (Carl Cochran, 1999, personal communication).

MARATHON COUNTY: Fluorite is a common component of the igneous rocks around Wausau. Fluorite is a widespread common accessory in the Nine Mile granite (Patton et. al., 1989). Falster (1987) reports fluorite is often found as purple to light blue masses and more rarely as cubes up to 4 cm. across in the granitic pegmatites of the Wausau pluton, such as are exposed in many quarries south of Rib Mountain.
— Fluorite forms dark purple masses in syenite of the wall zone of the Stettin pluton. Numerous outcrops occur in sec. 22 T.29N. R.6E. One good exposure is at “Zunker’s pit” (SW SE ) where fluorite is associated with euhedral zircon crystals. Fluorite is found in nepheline syenite at the old zircon quarry in SE SE . It is here associated with, micorperthite, albite, albite, aegirine, pyrochlore, apatite, eucolite as well as zircon crystals. (Stobbe and Murray, 1956; LaBerge and Myers, 1983). Fluorite is also found in a pegmatite dike with quartz, K feldspar, crocidolite, riebeckite, acmite, pyrochlore, and zircon at NW (Weidman, 1907).
— Purple masses and films of fluorite occur in shear zones in syenites at cuts and excavations in SE Sec. 27 T.29N R.7E on the western edge of Wausau. (LaBerge and Myers, 1983).
— Fluorite is common in syenite and nepheline syenite in the NE Sec. 29 T.29N R.7E (Weidman, 1907).
— Fluorite is found at the Summit Mine at the intersection of County O and U about 3 miles NW of Wausau where it is associated with aegirine and uranophane (Weidman, 1907).
— Fluorite occurs in gray syenite at NE NW Sec. 23 T.29N R.6E (Vickers, 1956).
Fluorite is common in granitic rocks exposed in a quarry in the NE sec. 6 T.27N. R.7E. (Brown, 1995, personal communication)
Fluorite occurs as purple to blue massive material in cavities in granite and as rare yellow octahedra in quartz veins at the Koss quarry, south of Rib Mountain. The yellow fluorite fluoresces yellow in shortwave ultraviolet light. (Buchholz, Falster, and Simmons, 1999).
— Fluorite occurs abundantly in the pegmatites at the Red Rock Granite North Pit (along Spring Brook Road) and the Ladick Quarry (sec. 19 and 20 T. 27N. R.6E.) (Buchholz and Simons, 2002).

MARINETTE COUNTY: Fluorite is found in granite in Sec. 7 T.38N R.20E (Van Alstine, 1976).
Fluorite is found along joint surfaces and in veins cutting granite at the Camp Five molybdenite deposit, about 4 miles northwest of Middle Islet in SW NW Sec. 18 T.33N R.20E. It is associated with molybdenite, pyrite, hematite and ferrimolybdite (Fisher, 1965; Greenberg, 1985).

OUTAGAMIE COUNTY: Fluorite forms tiny clear cubes, sometimes with hematite (?) inclusions at the Brugger Road Quarry, 14.5 miles south of Bonduel (Carl Cochrane, 1999, personal communication).

SAUK COUNTY: Fluorite is a rare component of rhyolite exposed along both sides of the Lower Narrows of the Baraboo River in sec. 20 and 23 T.12N R.7E (Stark,1932).
— Small cubes of purple fluorite occur in a glacial erratic granite boulder found in the Jesse Pit, near Baraboo, WI NW Sw sec. 15 T.11N. R.7E. Associated minerals include anatase, fluorapatite, zircon and unidentified thorium and LREE-carbonate minerals (Buchholz, 2003).

WAUPACA COUNTY: Fluorite is widespread as an accessory mineral in Wolf River Batholith. Examples of fluorite-bearing rocks occur south of Big Falls, along the Little Wolf River at SE SE Sec. 26 T.25N R.12E and in a quarry in Waupaca Adamellite in the NW NW Sec. 4 T.22N R.12E (Greenberg and others, 1986).
— Fluorite was reportedly associated. with uranium at the Anklam prospect (S 1/2 Sec. 23 and N 1/2 Sec. 26 T.25N R.12E) about 1 mile NE of Big Falls on County G (WGNHS files).
— Fluorite occurs in a pegmatite exposed in a highway expansion on County G about 1 mile east of Big Falls (Tom Buchholz, 2002, personal communication).

WINNEBAGO COUNTY: Fluorite was found at the Neenah Quarry, located on the SE edge of Neenah “below the city park and about 1000 feet west of Lake Winnebago” (Bagg, 1918). It was associated with calcite, galena, and pyrite in vein fillings and along joint surfaces in dolomitic limestone (Van Alstine, 1976).
— Fluorite occurs as clear to pale purple xls. in vugs with dolomite and pyrite at a Quarry, 3 miles west of Winchester on Route 110 (Carl Cochrane, 1999, personal communication).

WOOD COUNTY: Fluorite is found with chalcopyrite and quartz in veins cutting amphibolite at the Turner Quarry approximately 4 miles west of Pittsville (Crowns, 1976).
Fluorite forms massive purple vein fillings and yellow crystals in vugs in granite at the Fredrick Schill Quarry, NE of Vesper on east side of Hwy. 186. The fluorite fluoresces yellow in shortwave ultraviolet light (Buchholz, 1999).
— Fluorite occurs in quartz veins cutting granite in the Wood County quarry on the east side of Hwy B, near Cary Bluffs ( Sec. 25 T.24N. R.2E.) (Buchholz, personal communication).
— Fluorite occurs along fractures in granite quarried on the south side of Bluff Drive in the NW NE Sec. 34 T.24N. R.2E. (Van Wyck, 1995).
— Fluorite occurs as seams of white to pink cleavable material cutting granite at the John Cepress quarry, sect. 11 T.23N. R.2E. (Tom Buchholz, personal communication)
— Fluorite occurs in miarolitic cavities at the Haske Quarry, Sec. 25 T.24N. R.2E. It only rarely forms tiny crystals, but where it does can show cube, octahedral, and dodecahedral forms (Buchholz and others, 1998, 2005a).