Ferrovalleriite
Ferrovalleriite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula 2[(Fe,Cu)S]·1.53[(Fe,Al,Mg)(OH)₂].
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Valleriite structural group.
Key properties: Mohs hardness 1; specific gravity 3.72; Black streak; Metallic (fresh), dull, or tarnishes to iridescent golden-brown luster.
IMA symbol Fval, IMA status: approved, named in 1970.
Of low-temperature hydrothermal origin coating cavities in pentlandite-mooihoekite- cubanite ore with minor magnetite and chalcopyrite.
It is found associated with Ferrotochilinite, magnetite, an Fe-rich chlorite-type phyllosilicate, hibbingite, rhodochrosite.
As the structural analogue (based on chemical, X-ray, and IR data similarities) of valleriite with essential ferrous iron.