Monteneroite
Monteneroite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Cu²⁺Mn²⁺₂(AsO₄)₂·8H₂O.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Vivianite structural group.
Key properties: Mohs hardness 2; specific gravity 2.97; White streak; Vitreous luster; optically biaxial.
IMA symbol Mte, IMA status: approved, named in 2020.
Found as a secondary mineral in thin stratiform manganese ores located near the base of a chert sequence. Crystallized from As-, Cu- and Mn-rich fluids that circulated through fractures during the final stage of tectono-metamorphism.
It is found associated with Braunite, copper, cuprite, rhodochrosite, strashimirite.
The name refers to its type locality, the abandoned Monte Nero mine.