WGNHS
Wisconsin Geological and Natural History Survey

Gahnite

Dark green gahnite crystal on quartz with yellow chalcopyrite. Field of view is about 0.5 mm left to right. From Flambeau Mine, Ladysmith, Rusk County, Wisconsin. (Image by Dan Behnke.)

Formula: ZnAl2O4 Isometric

Description:

Green gahnite crystal on quartz. From Waterloo quarry, Dodge County, Wisconsin. Field of view is 1 mm left to right. Tom Buchholz specimen, Dan Behnke image.

Gahnite is an uncommon mineral found in schists and high temperature hydrothermal deposits.

DODGE COUNTY: Tiny aggregates of octahedral xls. were seen in pegmatites cutting quartzite in the Michels Materials Waterloo Quarry, NE sec. 33 and NW sec. 34 T.9N. R.13E. (Buchholz et al. , 2003, 2005)

RUSK COUNTY: Tiny green xls found at the Flambeau Copper Mine south of Ladysmith associated with tetrahedrite-tennanitite were tentatively identified as gahnite after SEM-EDS analysis. (Tom Buchholz, 1997, personal comunication)