Yellowish crystal aggregates of the rare phosphate rosemaryite from one of the few localities known worldwide: Gatumba Pegmatite, Ngororero, Western Province, Rwanda . Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Rosemaryite
Rosemaryite is an IMA-recognized mineral species in the phosphate class, with the chemical formula NaMn²⁺(Fe³⁺Al)(PO₄)₃.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Alluaudite-Wyllieite structural group.
Key properties: Mohs hardness 4; specific gravity 3.63; Resinous luster; optically biaxial.
IMA symbol Rmy, IMA status: approved, named in 1979.
Found in zoned complex granite pegmatites.
It is found associated with Trolleite, alluaudite, montebrasite, scorzalite, strengite (Buranga, Rwanda).
The mineral was named to honor Mrs. F. Rosemary Wyllie, wife of Professor Peter J. Wyllie, namesake of wyllieite, q.v.