Mineral Species: Vanadinite

Chemical Formula: Pb5(VO4)3Cl

Chemical Name: Lead Chlorovanadate

Mineral Class: Vanadates

Mineral Notes: Vanadinite is a secondary mineral formed by alteration of lead ore by water. The mineral is light sensitive and so specimens should be kept in the dark. The bright orange colouration gradually darkens and dulls to shades of brown.  Vanadinite is part of a chemical series with two other minerals Pyromorphite  and Mimetite. This series is a little different from most chemical series which involve substitution of the metallic ions such as calcium for magnesium. Instead, this series substitutes its anion groups; phosphate (PO4), arsenate (AsO4) and vanadate (VO4).

Description: An unusual form of Vanadinite, where the mineral is present as small, barrel-like, crystals. The colour is a mixture of orange and brown, the brown shade probably coming from the presence of small amounts of Mimetite. The specimen has a rather attractive waxy luster.

Location: JC Holmes Claim, Santa Cruz Co., Arizona, USA.