Vanadinite, a member of the Apatite group, crystallizes in the form of globular masses, barrel-shaped crystals, acicular crystals, hair-like formations, and prismatice and, rarely, as hollow prismatic crystals.
The vanadate analogue of Mimetite and Pyromorphite. Forms a solid solution series toward Mimetite In nature up to approximately V:As = 1:1 (Mimetite-Vanadinite Series), and a series with Pyromorphite. Baker (1966) showed by synthesis that there is a complete series between mimetite, pyromorphite and vanadinite.Vanadinite is a secondary lead chlorovanadate. It is chemically related to otherwise much more structurally complex but chemically similar to erikjonssonite, hereroite, janchevite, and kombatite. It is 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.First discovered by Señor A.M. del Rio (1764-1849), Professor, School of Mines of Mexico, Zimapan, before the element vanadium was discovered in 1830.
Chemical Composition: Pb5(VO4)3Cl
Hardness: 2.5 - 3
Barite crystallizes as tabular crystals, aggregates, plate-like masses, fibrous masses, and, occasionally, stalactites. The mineral occurs in a range of colours including colourless, blue, white, grwy, yellow, brown, and a brownish rose. Barite (aka Baryte) was first reported in 1800 by D.L.G. Karsten and was named for the Greek word meaning "heavy", referring to the mineral's high specific gravity.
Chemical Composition: BaSO4