Cadvanite

cadvanite

brochantite

chalcomenite

volborthite

Images

Formula: Cd(VO3)2
Valence: Cd(V5+O3)2
Vanadate of cadmium
Crystal system: Monoclinic
Specific gravity: 4.210 calculated for both the empirical and ideal formulae
Hardness: 2½ to 3
Streak: Pale yellow
Colour: Brownish yellow
Solubility: Slowly soluble in dilute hydrochloric acid at room temperature
Environments

Sedimentary environments
Hydrothermal environments

Cadvanite is a new mineral, approved in 2025 and to date (April 2026) reported only from the type locality.

Localities

The type locality for cadvanite, the Burro Mine, San Miguel County, Colorado, USA, is the type locality for 13 other minerals: ammoniolasalite, ammoniomathesiusite, ammoniozippeite, amurselite, bobfinchite, burroite, caseyite, metamunirite, metauroxite, nitroplumbite, okieite, protocaseyite and uroxite. In the Uravan Mineral Belt, in which the Burro Mine is situated, uranium and vanadium minerals occur together in bedded or roll-front deposits in sandstone. The uranium and vanadium ore mineralisations were deposited where solutions rich in uranium and vanadium encountered pockets of strongly reducing solutions that had developed around accumulations of carbonaceous plant material. Secondary (post-mining) mineralisation forms from the oxidation of uraninite - montroseite - corvusite assemblages in a moist environment. Under ambient temperatures and generally oxidising near-surface conditions, water reacts with pyrite to form aqueous solutions with relatively low pH (acidic). The various secondary phases that form depend upon prevailing conditions, as well as upon local enrichments in a variety of other elements.
Cadvanite is very rare, so far (2026) having been found on only a few micromount samples. It occurs on a matrix composed of quartz grains, covelliteklockmannite and cadmoselite; it is associated with brochantite, chalcomenite, clinochalcomenite, gypsum, volborthite and a potentially new Cu-Cd-sulphate mineral.
The substitution of Cd2+ for Zn2+ in mineral structures accounts for the relatively low abundance of Cd oxysalt minerals in nature. Only 18 oxysalt mineral species, including cadvanite, contain cadmium as an essential element. Zinc minerals are notably absent in the cadvanite assemblage, though the zinc divanadate, martyite, is found in other parts of the Burro mine.
Cadvanite occurs as poorly formed brownish yellow blades up to about 50 microns in length. More commonly, it occurs as irregular grains less than 10 microns across (CJMP 64.2.185-193).
Cadvanite from the Burro Mine - Image

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