Cadvanite, a New Cadmium Vanadate from the Burro Mine, San Miguel County, Colorado, USA

Abstract Cadvanite (IMA2025-005), CdV2O6, is a new mineral discovered at the Burro mine, Slick Rock district, San Miguel County, Colorado, USA. It was found in a secondary efflorescent assemblage on matrix composed of quartz grains, covellite–klockmannite, and cadmoselite and it is associated with brochantite, chalcomenite, clinochalcomenite, gypsum, and volborthite. The mineral occurs as poorly formed brownish-yellow blades. The streak is pale yellow, the luster is dull, silky, or adamantine, the Mohs hardness is about 2½–3, the tenacity is brittle, the fracture is splintery, and there are probably two cleavages, possibly {100} and {001}. The calculated density is 4.210 g/cm3. Electron probe microanalysis provided the empirical formula Cd1.00V2.00O6. Cadvanite is monoclinic, space group C2/m, a = 9.831(10), b = 3.6220(9), c = 7.051(5) Å, β = 103.97(2)°, V = 243.65(7) Å3, and Z = 2. In the crystal structure (R1 = 0.0505 for 1210 I > 2σI reflections), Cd2+O6 octahedra form a straight edge-sharing chain and the V5+O5 polyhedra form a zig-zag edge-sharing [VO3]− chain. The two chains link to one another by corner sharing to form a three-dimensional framework.