Rakovanite, (NH₄)₃Na₃(V₁₀O₂₈) · 12H₂O; formerly given as Na₃(H₃V₁₀O₂₈)^.15H₂O; later, the ammonium ion was shown to be present and essential, is a member of the pascoite family. It is a transparent,

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Br ...

mineral occurring in the

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystal system. It is orange in color and has an orange-yellow colored streak. Rakovanite is soft with a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by t ...

of 1 and a calculated

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of 2.407g cm⁻³. It does not fluoresce in long- or short-wave ultraviolet radiation. Rakovanite crystals are up to one mm in maximum dimension and vary in habit from blocky to prismatic on 01 commonly exhibiting steps and striations parallel to 01 Its name honors John Rakovan, former professor, Department of Geology and Environmental Earth Science,

Miami University Miami University (informally Miami of Ohio or simply Miami) is a public research university in Oxford, Ohio. The university was founded in 1809, making it the second-oldest university in Ohio (behind Ohio University, founded in 1804) and the ...

, State Mineralogist and Senior Museum Curator
New Mexico Bureau of Geology and Mineral Resources

Occurrence

Rakovanite was found on specimens from the Sunday mine and the West Sunday mine, Slick Rock district, San Miguel County, Colorado, US. It occurs as crystalline crusts on sandstone fractures in the mine walls of the Sunday and West Sunday mines. The best crystals were found perched on an amorphous dehydrated vanadium phase along with crystals tightly adhered to a corvusite-montroseite matrix. It forms from the oxidation of montroseite- corvusite assemblages. It is associated calcite, corvusite, hewettite, hughesite, montroseite, munirite,

paramontroseite Paramontroseite (V4+O2) is a relatively rare orthorhombic vanadium oxide mineral in the Ramsdellite group. Synthetic paramontroseite may have applications in medicine, batteries and electronics. Name The name Paramontroseite is derived from the ...

, pascoite, rossite, sherwoodite, and other unidentified vanadium phases as well as at least two other potentially new decavanadate species. It forms aqueous solutions of relatively low pH when water reacts with pyrite in the deposit under ambient temperatures and generally oxidizing near-surface environments.

Atomic arrangement

Rakovanite crystal unit consists of the decavanadate polyanion similar to that found in other decavanadate-bearing mineral. The decavanadate polyanion is formed of ten distorted, edge-sharing octahedra.

Chemical composition

The empirical formula with calculated H₂O and (NH₄)₂O contents is NH₄)_2.94K_0.06sub>Σ3.00(Na_2.97Al_0.01 Ca_0.01)_Σ2.99 ₁₀O₂₈2H₂O (–0.01 H for charge balance) and the ideal formula is (NH₃)₃Na₃ ₁₀O₂₈2H₂O.

References

{{Reflist, 30em Oxide minerals Monoclinic minerals Minerals in space group 14

Occurrence

Atomic arrangement

Chemical composition

See also

References