Nepheline (Na,K)AlSiO4 Hexagonal

Description: Nepheline occurs as a grayish to palely colored vitreous massive mineral in low-silica syenites, phonolites and metamorphic rocks derived from them.

MARATHON COUNTY: Nepheline is a major constituent of the nepheline syenite exposed in the outer rim of the Stettin Pluton west of Wausau. It forms gray to bluish to pinkish anhedral grains associated with K feldspar, sodalite, cancrinite, zircon, fluorite, riebeckite, aegirine, hastingsite, hedenbergite, fayalite, apatite, monazite and other minerals (Weidman, 1904, 1907b; Stobbe and Murray, 1956; Sood et. al., 1980). Some rocks may consist of as much as 25% nepheline. In pegmatitic phases the nepheline grains may be as much as 30 cm. long. Some nepheline-bearing localities are:
- as loose xls. over 2 cm. across in the SE sec. 1, T.29N. R.6E. (Weidman, 1907b).
- in outcrop in SW sec. 2 T.29N. R.6E. (Sood et. al., 1980).
- in outcrop SE sec. 4 T.29N. R.6E. (Weidman, 1907b).
- as masses up to 15 cm. across in SE NW sec. 5 T.29N. R.6E. (Weidman, 1907b).
- in outcrop NW sec. 15 T.29N. R.6E. (Weidman, 1907b).
- as blocky pinkish grains altering to cancrinite and other minerals in dikes in the quarry and outcrops in SE SE sec. 22, and nearby sec. 26 and 27 T.29N. R.6E. (Stobbe and Murray, 1956; Sood et. al., 1980).
- in outcrop NW sec. 24 T.29N. R.6E. (Weidman, 1907b).
- in outcrop NE sec. 27 T.29N. R.6E. (Weidman, 1907b).
- as pinkish grains 1-2 cm. across in a syenite pegmatite in a roadcut along County U 1 km. east of the Little Rib River, SW SW sec. 18 T.29N. R.7E. (Myers, et. al., 1984).
- in outcrop NW sec. 28 T.29N. R.7E. (Weidman, 1907b).
- in outcrop in NE sec. 29 T.29N. R.7E. (Weidman, 1907b).
- in outcrop in NE sec. 31 T.29N. R.7E. (Weidman, 1907b).
- in outcrop sec. 2 T.28N. R.8E. (Weidman, 1907b).

Return to Wisconsin Mineral List