Very dark green crystal frgament of the rare vanadium mineral doloresite from Monument #2 Mine, Yazzie Mesa, Apache County, Arizona, United States of America. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Doloresite
Doloresite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula V⁴⁺₃O₄(OH)₄.
It crystallizes in the monoclinic crystal system (space group C2/m).
Key properties: specific gravity 3.27–3.33; Greenish black streak; Submetallic; sometimes satinlike on cleavage surfaces luster.
IMA symbol Dlr, grandfathered status — known before the IMA’s founding, named in 1957.
Found in relatively unoxidized uranium-vanadium ores; from the cores of black, concretionary masses high in uranium and vanadium, surrounded by tyuyamunite-bearing sandstone (La Sal No. 2 mine, Colorado, USA).
It is found associated with Coffinite, uraninite, clausthalite, montroseite, paramontroseite, vanadium oxides.
The name refers to the Dolores River, southwestern Colorado, USA.