WGNHS
Wisconsin Geological and Natural History Survey

Microlite

Yellow crystal of microlite in a small cavity in granite, from the Wimmer #3 Pit, Marathon County. Tom Buchholz specimen. Dan Behnke image. Field of view is 0.2 mm left to right.

Formula: (Na,Ca)2Ta2O6(O,OH,F) Isometric

Description:

Microlite refers to a group of  rare minerals related to pyrochlore that form equant to irregular pale yellow, brown, red or green grains in complex granite pegmatites.

FLORENCE COUNTY: Microlite occurs with lepidolite and many other minerals in the Animikie Red Ace complex pegmatite in sec. 22 T. 39N. R.17E. near the Pine River (Falster, et al., 1995).

MARATHON COUNTY: Crude brown crystals of microlite up to 2 mm across are found in the pegmatites of Wausau Pluton (Falster, 1981). Microlite has been noted at the Koss Pit (SW sec. 2 T27N R.5E), the Red Rock Granite North Pit (along Spring Brook Road), the Ladick Quarry (sec. 19 and 20 T. 27N. R.6E.) and the Wimmer #3 pit (NW sec. 19 T.28N R7E) (Buchholz and Simons, 2002, Buchholz et al., 2004).