A good looking Vanadinite Crystal Specimen. Known for its hexagonal shaped crystals and orange brown colouring. Quite an unusual colour among minerals and often on matrix. This will make a good display specimen in someones mineral collection. Pics taken with good sun light make the crystals look a lustrous orange brown. Good coverage on top with a few chunky crystals, all the crystals are well formed and lustrous.
8cm x 5.6cm x 3cm, 130g.
Vanadinite is a secondary mineral in the oxidized zone of lead bearing deposits. Almost always found in the oxidation zone of lead deposits. In arid climates resulting from the alteration of vanadiferous sulphides and silicates of the gangue and wall rocks.
Vanadinite is one of the main industrial ores of the metal vanadium and a minor source of lead. 80% is used as a steel additive. Vanadium steel alloys are very tough, used for armour plate, axles, tools, piston rods and crankshafts. Less than 1% of vanadium, and as little chromium, makes steel shock resistant and vibration resistant. The oxide is used as pigment for ceramics and glass. Also as a catalyst in producing superconducting magnets.
The mineral Vanadinite shares the same structure with Apatite and the two share similar crystal shapes at times. Vanadinite is part of a chemical series with two other minerals; Pyromorphite (Pb5(PO4)3Cl) and Mimetite (Pb5(AsO4)3Cl). This series is a little different than most chemical series which involve substitution of cations such as calcium for magnesium. Instead, this series substitutes its basic chemical units the anion groups phosphate (PO4), arsenate (AsO4) and vanadate (VO4).
Vanadinite is usually red which the other members of this series and apatite group usually are not. Classic crystal habit is short hexagonal prisms terminated by a pinacoid flat basal face. These crystals are wider than they are long. More blade like than the barrel shaped crystals so common to the Apatite Group minerals. The high luster and deep red color give vanadinite a nice appeal to mineral collectors.
Color is typically bright red to orange, less commonly gray or brown.
Luster is vitreous to adamantine.
Transparency crystals are transparent to translucent.
Crystal System is hexagonal; 6/m
Crystal Habit is typically the hexagonal prism with pinacoid as a termination. Rare crystals can have the hexagonal pyramid as a termination. Also found as rounded masses and crusts.
Cleavage is none.
Fracture is conchoidal.
Hardness is 3.
Specific Gravity is approximately 6.6+ (very heavy for translucent minerals)
Streak is yellowish white.
Associated Minerals are wulfenite, limonite, barite, galena and secondary lead deposit minerals.
Other Characteristics: index of refraction is 2.39 (typically high for lead minerals).
Notable Occurances include Arizona, USA; Mexico; Tsumeb, Nambia; Zambia; and South Africa.
Best Field Indicators are color, crystal habit, high luster and density.