Wulfenite: a colourful gemmy lead-molydenum mineral species
The mineral species Wulfenite is a tetragonal lead molybdate, PbMoO4. Molybdates belong to the larger class of Sulfate minerals. Wulfenite forms a series with Stolzite, PbWO4, a tetragonal wolframate and is a member of the Scheelite group: A(XO4), a group of tetragonal molybdates and tungstates. Wulfenite is mostly a secondary mineral typically found as thin tabular crystals with a bright orange-red, yellow-orange, yellow or yellowish grey colour in the oxidised zones of hydrothermal lead deposits. Wulfenite is a favorite among mineral collectors because of its tabular crystals and various colours.
It was named after the Austrian mineralogist Franz Xavier von Wulfen (1723-1805) and originally discovered (type locality) at Bad Bleiberg, Bleiberg District, Gailtaler Alpen & Karnische Alpen, Carinthia, Austria. Located in southwestern Austria, just north of a three country junction between Austria, Italy and Slovenia, this locality is a baryte-lead-zinc mineralization, typical of stratabound Galena and Sphalerite, within Triassic limestones and intercalated carbonates. This locality is also the type locality for Hydrozincite (zinc carbonate; monoclinic) and Ilsemannite (molybdenum oxide; amorphous).
Five varieties of this mineral species are currently recognized: Calcian Wulfenite with Ca partially replacing Pb, Chillagite Pb[(Mo,W)O4], Chromian Wulfenite Pb(Mo,Cr)O4, Tungstenian Wulfenite or W-rich Vanadinite, and Vanadian Wulfenite with V partially replacing Mo.
There are over seventeen hundred known localities worldwide (currently 1745 reported localities on mindat.org) where Wulfenite has been identified. Best specimens of this mineral species for their crystal size, perfection and various colours have been found in Xinjiang Province of China, northern Mexico, Mibladen and Touissit districts of Khénifra Province in Morocco, Tsumeb in Namibia, Arizona State of United States, and northern Slovenia near its border with Austria (near its locality type).
Collectors who wish to investigate further the geology and mineralogy of Wulfenite and find excellent photographs of this colourful mineral species are invited to consult the mindat.org website as well as the Mineralogical Record publications (especially volume 11, number 3, 1980).
Text published: December 2016.