Fluorescent Minerals in Wisconsin

One of the things that can turn people on to minerals and mineral collecting is seeing minerals take on unexpected colors when exposed to ultraviolet light. As part of my efforts at a compilation of a minerals of Wisconsin database, I have been interested in gathering information on those minerals in the state that are significantly fluorescent. Below is a summary of some observations made on specimens from the state in the collections of the University of Wisconsin River Falls. I hope this encourages others to check their collections and let me know of additions to this list.

Calcite - Manganocalcite from the Montreal and adjacent mines near Montreal, Iron County, Wisconsin occur in spherical masses that fluoresce red in short wave. U.V. Several calcite scepter crystals from the Shullsberg area in Lafayette County fluoresce deep red under short wave U.V.
- Red fluorescing calcite is also found at the Mathy (Tork) Quarry in Wisconsin Rapids. A small amount of calcite was found at the Flambeau Copper Mine, near Ladysmith. Most of it was not fluorescent, but some had zones that fluoresced red. One vug had calcite that fluoresced orange under short wave U.V. and yellow under long wave U.V.
- Calcite in the form of travertine from various exposures in the Prairie du Chien Group and Platteville Formation in Buffalo, Pepin, Pierce and St. Croix Counties fluoresces and phosphoresces bluish-yellow in both short wave and long wave U.V. In general calcite from any part of the state should be checked for fluorescence and phosphorescence.

Dolomite - Much dolomite in the Prairie du Chien formation fluoresces and phosphoresces a dull bluish to yellowish in short wave U.V. light. This forms an interesting part of the fluorescent mineral display part of the tour in Crystal Cave, near Spring Valley, Wisconsin.

Fluorite - Fluorite from the Koss Pit near Wausau, Marathon County fluoresces blue, yellow or greenish in short wave U.V., sometimes in zonal patterns.
- Fluorite found as zoned clear, brown and yellow cubes in vugs in calcite in a quarry on the south side of Sturgeon Bay fluoresce and phosphoresce yellow in both long wave and short wave U.V.

Hydrozincite - Earthy hydrozincite coatings with sphalerite and other minerals from the zinc-lead district in Iowa, Lafayette and Grant counties fluoresce blue under short wave U.V.

K Feldspar - The K feldspar in the "rotten granite" and other granite quarries in Marathon and Wood counties will often fluoresce deep red in short wave U.V. K feldspar with epidote from the dumps of Jackson County Iron Mine near Black River Falls also fluoresces red.

Opal - Hyalite opal from the "rotten granite" quarries south of Rib Mountain in Marathon County fluoresce bright green in short wave and long wave U.V.

Quartz - Drusy to coarse quartz crystals, some with phantoms, were found in dolomite in a road cut on Hanley road, Hudson, St. Croix County. These fluoresce pale yellow in short wave U.V. Associated calcite and aragonite which fluoresce and phosphoresce blue in short wave and long wave U.V. Thus some samples will give 2 or 3 different fluorescent colors.
- Quartz in chert breccia from the quarry on Glover Bluff in fluoresces faint yellow, blue and green in short wave U.V. light.

Finally, although not strictly a mineral, slag from the iron smelting operation in Spring Valley, Pierce County, Wisconsin, fluoresces orange under short wave U.V.

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