Vanadinite

Vanadinite is a chlorinated lead vanadate that represents one of the most important vanadium minerals in nature. It belongs to the apatite group and crystallizes in the hexagonal system, forming characteristic prismatic crystals that can reach significant dimensions. Its coloration ranges from brilliant red to intense orange to brown, depending on impurity content and the oxidation state of vanadium. The mineral forms in secondary oxidation environments in the surface zones of lead and vanadium deposits, often associated with minerals such as cerussite, anglesite, wulfenite, and other secondary oxides and salts.

From a collector's perspective, vanadinite is highly prized for its vivid color and crystalline clarity. The most renowned deposits are found in Morocco (Mibladen, Touissit), southwestern United States (Arizona, New Mexico), Namibia, and Peru. Moroccan crystals are particularly sought after for their pure red color and well-developed forms. Despite its low hardness making it unsuitable for gemological use, it remains a fundamental specimen in quality mineralogical collections.

Composition: Pb₅(VO₄)₃Cl with possible substitutions of As for V and F for Cl. Crystal system: hexagonal, space group P63/m, cell parameters a = 10.35 Å, c = 6.88 Å. Mohs hardness: 2.5-3. Density: 6.8-7.2 g/cm³. Cleavage: none, conchoidal fracture. Luster: adamantine, transparency from transparent to translucent. Refractive index: nω = 2.350, nε = 2.416 (positive birefringent). Color: red, orange, brown; yellow streak. Pleochroism: weak to moderate. UV Fluorescence: yellow-green fluorescence under long-wave UV rays. Solubility: slightly soluble in dilute acids. Mineral associations: cerussite, anglesite, wulfenite, limonite, goethite. Genesis: secondary oxidation mineral in surface zones of lead and vanadium deposits, typical of arid climates. Diagnostic characteristics: red-orange color, hexagonal prismatic crystal habit, high density, acid solubility.