Orange crystal of the mineral of the rhodonite group: ferrorhodonite (IMA 2016-016), from the type locality in Broken Hill (New South Wales, Australia) and only one of the two known localities worldwide in a marix of galena. Ferrorhodonite can be distinguished from rhodonite by its brownish pink color. — Photo: David Hospital · CC BY-SA 4.0
Ferrorhodonite
Ferrorhodonite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaMn₃Fe(Si₅O₁₅).
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Rhodonite structural group.
Key properties: Mohs hardness 6; specific gravity 3.71; White streak; Vitreous luster; optically biaxial.
IMA symbol Frdn, IMA status: approved, named in 2016.
Forms during granulite facies metamorphism of a manganese-rich sedimentary exhalative lead-zinc-silver deposit.
It is found associated with Galena, chalcopyrite, spessartine, quartz.
As an analog of rhodonite with Fe2+ dominant in the M4 site of the structure.