WGNHS
Wisconsin Geological and Natural History Survey

Alluaudite

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Square shaped black alluadite mass has white quartz on the upper left corner.
Dark green to black tarnished cleavable alluaudite mass with white quartz. Pleasant Valley pegmatite, Fourmile, Custer County, South Dakota. (Photo by W. Cordua.)

Formula: (Na,Ca)Mn2+(Mn,Fe3+,Fe2+,Mg)2(PO4)3 Monoclinic

Description:This is a series of rare phosphate minerals found in granite pegmatites.

FLORENCE COUNTY: Described as a component of tan to light brown phosphate nodules associated with apatite, heterosite-purpurite and schorl in the south end of a complexly zoned pegmatite in Florence County (Falster, Simmons and Moore, 1988).