Formula: Fe2+Fe3+2(PO4)2(OH)3.5H2O Triclinic
Ferristrunzite is a rare phosphate mineral formed by the alteration of other phosphates.
RUSK COUNTY: Ferristrunzite is found as bright yellow acicular crystals arranged in radial clusters in vugs and seams in massive cuprite/goethite with quartz at the Flambeau Mine, near Ladysmith. Verified by EDS and X-Ray analysis. (Buchholz, personal communication)