Vanadium

vanadium

brackebuschite

hewettite

cavansite

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Formula: V
Element, iron group. Until recently vanadium was thought not to occur in its native state in the Earth's crust.
Specific gravity: 6.033 calculated
Colour: Steel grey
Solubility: Resistant to attack by alkalis, hydrochloric acid, sulfuric acid and salt water (ChC)
Abundance: In the Earth’s crust, 120 parts per million by mass, 50 parts per million by moles; in the Solar System, 400 parts per billion by mass, 9 parts per billion by moles (ChC)
Environments

Fumeroles

When extracted from its ore vanadium is a bright white, soft, ductile metal with good structural strength. When present in compounds, it exists mostly as V⁵⁺ (ChC).

Localities

Vanadium is a new mineral (2016) found in sublimates of high-temperature fumaroles of the Colima volcano, Mexico. The mineral precipitates over a narrow temperature range of 550–680^oC, and occurs in association with colimaite and shcherbinaite. Native vanadium was found in natural incrustations and on the inner wall of a silica tube inserted into vents and subsequently in the adjacent rock of the “Z3 fumarole.” It forms smooth, irregular to flattened crystals, 5–20 μm in diameter with smaller irregular crystals observed in silica tubes (AM 101.2783).

Alteration

Vanadium oxidises in air at around 660^oC to the pentoxide V₂O₅ (shcherbinaite when naturally occurring) (ChC).

Vanadium-bearing minerals include:

Sulphides - the sulphide anion is S^2-
Sulphosalts - sulphide minerals with the general formula A_mB_nX_p, where A represents a metal, B usually represents a semi-metal and X is sulphur or rarely selenium and/or tellurium
Oxides - the oxide anion is O^2-
Chlorides - the chloride anion is Cl^-
Sulphates - the sulphate anion is (SO₄)^2-
Phosphates - the phosphate anion is (PO₄)^3-
Arsenates - Minerals that contain the radical (AsO₄)^3- or (AsO₃OH)^2-
Vanadates - Minerals that contain the radical (V⁵⁺O₄)^3- or (V⁵⁺O₃)^-
Decavanadates - Minerals that contain the [V₁₀O₂₈]^6– polyanion
Arsenovanadates - Minerals that contain the polyoxymetalate cluster [As⁵⁺V⁵⁺₁₂O₄₀(VO)]^12-
Nesosilicates - insular (Si⁴⁺O₄)^4- groups
Sorosilicates - (Si⁴⁺₂O₇)^6- groups
Cyclosilicates - (Si⁴⁺_nO_3n)^2n- groups
Inosilicates - single chain - (Si⁴⁺_nO_3n)^2n- groups
Phyllosilicates - (Si₂O₅) groups
Tectosilicate - [Al³⁺_xSi⁴⁺O_yO_(2x+2y)]^x−
Polyoxovanadosilicate - [(V⁴⁺,V⁵⁺)₅O₁₇] groups

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