Kyanite

Formula: Al₂SiO₅Triclinic

Description:

Kyanite schist outcrop near Powell in Iron County, Wisconsin. *(Photo courtesy Tod Roush.)*

Kyanite is formed by the metamorphism of alumium-rich rocks, and is often associated with biotite, muscovite, almandine, staurolite, and sillimanite. It is indicative of relatively high pressures during metamorphism.

ASHLAND COUNTY: Kyanite is reported in schists and gneisses outcropping in the W 1/2 of Sec. 14 and the NE Sec. 22 T.41N R.1E, west of Butternut (King, 1882).

IRON COUNTY: Kyanite occurs in gneisses and schists in the Powell area, in Sec. 28, 29, 32, 33 T.42N R.4E. It can be found in a roadcut on Hwy. 182 west of Powell at SE SE Sec. 28 (Mudrey, 1979), associated with almandine, staurolite, biotite, and plagioclase. It is found in a series of small outcrops in NE NE Sec. 33 (WGNHS files). It is also found with staurolite and almandine at NE NW Sec. 23 T.42N R.4E (Sims et al., 1989). The crystals at these outcrops are subhedral and up to 3 cm long. They often contain many quartz inclusions. Attempts to produce kyanite economically from these outcrops in the 1930s were unsuccessful. Kyanite is reported in schists and gneisses in the SE Sec. 35 T.42N R.3E, south of Mercer (King, 1882). Kyanite was also reported from NW Sec. 3 T.41N R.2E (King, 1882).

Light-blue kyanite crystal (center, about 0.6 cm long) with garnets in quartz biotite. Scale in inches. *(Photo courtesy Tod Roush.)*

FLORENCE COUNTY: Kyanite is reported in quartz veins with specular hematite at the Pine River Reservoir, about 5 miles south of Florence (Nilsen, 1964).

JACKSON COUNTY: Kyanite is reported as a minor accessory in the biotite schist and talc schist associated with the iron formation at the Jackson County Iron Mine, east of Black River Falls (SE Sec. 15 T.21N R.3W) (Jones, 1978). Andalusite and sillmanite are also reported from the mine.

SAWYER COUNTY: Kyanite biotite schist has been found in a shallow excavation on the south side of Blaisdell Lake, N of Loretta, in the NW NE Sec. 16, T.40N R.4W (Dixie Carroll, personal communication, 1990).

VILAS COUNTY: Float blocks of gneiss containing kyanite were found at the narrows between Spider Lake and Island Lake in the SE Sec. 13 T.42N R.5E (Allen and Barrett, 1914).

—Core recovered from the NW Sec. 2 T.42N R.10E south of Land O’Lakes contained 34 feet of kyanite-bearing gneiss with associated staurolite (Allen and Barrett, 1914).