One of the things that can turn people on to minerals and mineral collecting is seeing how some minerals take on unexpected colors when exposed to ultraviolet light. Shown below are paired photos of some of Wisconsin’s fluorescing minerals—plain light on the left side of the photo, shortwave ultraviolet (UV) light on the right.
Calcite
Calcite cleavage, from near Fountain City, Wisconsin. Specimen is about 8 cm across. (Photo credit: Harold Moritz)

Manganoan Calcite
Manganoan calcite crusts on hematite from the Montreal Mine, Iron County, Wisconsin. Specimen is about 10 cm across. This type of calcite is rich in manganese. (Photo credit: Harold Moritz)

Fluorite
Cubic crystals on chert, from Sturgeon Bay, Wisconsin. Specimen is about 4 cm across. (Photo credit: Harold Moritz)

Hyalite
Crust of hyalite opal on granite from Koss Pit, near Wausau, Wisconsin. Specimen is about 16 cm across. (Photo credit: Harold Moritz)

Zircon and Potassium Feldspar
Brown zircon crystals on potassium feldspar, from Zunker’s Pit, near Stettin, Wisconsin. Under UV light, the zircon glows yellow and the potassium feldspar fluoresces pink. Specimen is about 4.5 cm across. (Photo credit: Harold Moritz)

Strontianite
Spherical aggregates of white strontianite on dolostone, from Mackville, Wisconsin. Specimen is about 4 cm across. (Photo credit: Harold Moritz)
