Several black crystal aggregates of the rare vanadium mineral melanovanadite from Ragra mine, Peru. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Melanovanadite
Melanovanadite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Ca(V⁵⁺,V⁴⁺)₄O₁₀·5H₂O.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2.5; specific gravity 2.55; Dark reddish brown streak; Submetallic luster; optically biaxial.
IMA symbol Mvd, grandfathered status — known before the IMA’s founding, named in 1921.
Found in altered black shale in a very rich vanadium deposit (Minasragra, Peru); in Colorado Plateau-type U–V deposits.
It is found associated with Pascoite, pyrite, copper, gypsum, patrónite, sherwoodite (Minasragra, Peru); duttonite (Peanut mine, Colorado, USA).
Its name comes from the Greek for black, for the color, and VANADium in the composition.