COLUMBITE-TANTALITE (Fe,Mn)(Nb,Ta)2O6 Orthorhombic

Description: Columbite-tantalite refers a group of minerals having varying amounts of iron, manganese, niobium and tantalum. They are found as platey black grains in complex granitic pegmatites.

DODGE COUNTY: Tiny prismatic xls. of manganocolumbite and manganotantalite 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, 2005b)

FLORENCE COUNTY: Small platey crystals and sprays usually 1-2 mm. across and occassionly up to 1 cm. in diameter are commonly associated with albite, spodumene and other minerals in the complex pegmatite dike swarm in Fern Township. Such pegmatites are widely exposed in Sec. 22 T.39N. R.17E (Kohler, 1988, 1989). Columbite-tantalite is also found as xls. up to 2 cm in a pegmatite in the NE SW SE Sec. 29 T.39N R.17E (Koehler, 1989, personal communication). Some of this material has been shown to be manganocolumbite and manganotantalite (Falster et. al., 1995).

MARATHON COUNTY: Falster (1987) notes small stubby black crystals of columbite-tantalite rimmed by an unknown yellow mineral in a few pockets in the Wausau pluton, such as exposed in the granite quarries south of Rib Mountain.
- Ferro-columbite, ferro-tantalite, mangano-tantalite, mangano-columbite and tantalum-bearing ferro-columbite at the Koss pit south of Rib Mountain. (Buchholz, Falster and Simmons (1999), Buchholz and Simmons, 2002).
- Ferro-columbite, ferro-tantalite, mangano-tantalite, mangano-columbite and tantalum-bearing ferro-columbite at the Wimmer #3 pit south of Rib Mountain. (Buchholz, Falster and Simmons (1999), Buchholz and Simmons, 2002).
-Ferrocolumbite and manganotantalite are reported from the LaDick quarry, sec. 19, T.24N R5E (Buchholz et. al., 1999).
- Ferro-columbite, ferro-tantalite, mangano-tantalite, mangano-columbite and tantalum-bearing ferro-columbite at the Red Rock Granite North Pit pit and Maguire Pit along Spring Brook road south-west of Rib Mountain. (Buchholz and Simmons, 2002, Buchholz et. al., 2004).

SHAWANO COUNTY: Tiny crystals of columbite-tantalite a few mm across are found in the complex pegmatite exposed south of the Tigerton Dells near Tigerton in the NE 1/4 SW 1/4 NE 1/4 Sec.15 T.26N R.12E. Associated minerals include gadolinite, allanite, beryl and phenakite (W.G.N.H.S. files, 1986).

WOOD COUNTY: Tiny crystals of ferrocolumbite a few mm across are found in the granite at Haske Quarry, sec. 25 T.24N. R.2E. (Buchholz et. al., 2005a). - Well formed crystals up to 4mmm of "mostly manganoan tantalian ferrocolumbite" was found in granite in the Magurie Pit, part of the LaDick East quarry complex east of Wausau. (Buchholz et. al. , 2005a)

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