Vanadinite: a very colourful mineral species
The mineral species Vanadinite is an hexagonal lead-rich vanadate, Pb5(VO4)3Cl. Vanadates belong to the Apatite group of mineral species within the larger class of phosphate minerals. Vanadinite is isostructural (identical crystal structure) with Mimetite Pb5(AsO4)3Cl and Pyromorphite Pb5(PO4)3Cl, respectively the arsenate and phosphate equivalent of Vanadinite (a vanadate). Vanadinite is mostly a secondary mineral typically found as hexagonal crystals with a bright orange-red, red-brown, brown, bright red colour in the oxidized zones of lead deposits in arid climates. It can also be yellow, whitish; pale straw-yellow; colourless or weakly tinted in transmitted light. It is the result of alteration of vanadium-rich sulphides and silicates. Vanadinite is a favorite among mineral collectors because of its sharp hexagonal crystals and bright colours.
It was named for its vanadium content and originally discovered (type locality) in 1830 at Zimapán, Municipality de Zimapán, Hidalgo, Mexico. It is located more or less in central Mexico, about 200 km North of Mexico City. Zimapán is also the type locality of Hidalgoite PbAl3(SO4)(AsO4)(OH)6, a trigonal lead-aluminium arsenate.
There are currently two recognized varieties of this mineral species: Arsenatian Vanadinite Pb5[(V,As)O4]3Cl, formely known as Endlichite, and Cuprian Vanadinite (Pb,Cu)5(VO4)3Cl also known as Cuprovanadinite.
There are six hundred seventy reported localities worldwide (on mindat.org) where Vanadinite has been identified. Best specimens of this mineral species for their crystal size, perfection and colours include Mibladen and Touissit districts of Khénifra Province in Morocco, Tsumeb in Namibia, Arizona and New Mexico States of United States.
Collectors who wish to investigate further the geology and mineralogy of Vanadinite and find excellent photographs of this colourful mineral species are invited to consult the mindat.org website as well as the Mineralogical Record publications.
Text published: December 2016.