Formula: (Mg,Fe)7Si8O22(OH)2 Orthorhombic
Description: Anthophyllite is a mineral formed from the metamorphism of magnesium-rich rocks. It is often associated with other amphibole minerals, pyrope, and cordierite.
JACKSON COUNTY: Anthophyllite occurs as long radiating fibrous crystals and masses intergrown with talc at the Jackson County Iron Mine, Sec. 15 T.21N R.3W near Black River Falls. Associated minerals are chlorite, biotite, magnetite, pyrite, cummingtonite and actinolite (Jones, 1978).
MARINETTE COUNTY: Anthophyllite is noted by Cummings (1978) in rocks associated with sulfide zones in the Quinnessec. Formation in T.36N R.18E. It is reported from the Duval massive sulfide body, Sec. 2 and 3 T.35N R.18E and Sec. 28 T.36N R.18E (Hollister and Cummings, 1982).
RUSK COUNTY: Anthophyllite occurs as “sheaf-like bundles of radiating needles” in a mineralized iron formation in the Eisenbrey massive sulfide deposit north of Ladysmith (NW sec. 17 T.35N. R.6W. (May, 1996).
WOOD COUNTY: Massive sheets of anthophyllite occur with talc and serpentine at the Milladore talc deposits (Milwaukee County Public Museum specimen).