Wulfenite

wulfenite

biehlite

molybdofornacite

lukrahnite

Images

Formula: PbMoO4
Molybdate, scheelite group, forms a solid-solution series with stolzite
Crystal System: Tetragonal
Specific gravity: 6.5 to 7.5 measured, 6.88 calculated
Hardness: 3
Streak: White
Colour: Yellow to orange-red, blue, grey
Solubility: Slightly soluble in hydrochloric, sulphuric and nitric acid
Common impurities: W,Ca,V,As,Cr,W,Ti
Environments:

Carbonatites
Hydrothermal environments (typical)

Wulfenite is a secondary mineral that generally forms in massive hydrothermal replacement deposits. It is also found in the oxidation zone of hypothermal (high temperature) lead veins with other secondary lead minerals, especially cerussite, vanadinite and pyromorphite, and in carbonatites.

Localities

At the Nakhlak Mine, Anarak District, Nain County, Isfahan Province, Iran, epigenetic (formed later than the surrounding or underlying rock formation) vein deposits and metasomatic replacement bodies are hosted by a chalky Upper Cretaceous (100.5 to 66 million years ago) limestone. The limestone underwent dolomitisation prior to sulphide mineralisation. The principal primary ore mineral is galena, associated with minor or trace amounts of sphalerite, tetrahedrite -tennantite, pyrite and chalcopyrite as inclusions. The main secondary ore mineral is cerussite, sometimes associated with minor amounts of anglesite, plattnerite, wulfenite, minium, mimetite, covellite, chalcanthite, malachite and goethite. Many trace elements are present in the primary galena, but most notably it is rich in silver and antimony and poor in bismuth.
Although much rarer at the mine than cerussite, occasional pockets of rather fine wulfenite specimens have been collected. Wulfenite occurs as typical square tablets up to 2 cm or so, modified by pyramid faces. Trace amounts of silicon, tungsten, calcium and vanadium have been detected in the wulfenite. The colour ranges from yellow and yellow-orange to red-orange and bright red.
Attractive specimens of bright red wulfenite have also come from the Chah-Kharboze mine, just 6 or 7 km south of Nakhlak. The Chah-Milleh mine, about 6 km south of Chah-Kharboze, has produced attractive red-orange wulfenite crystals, some with red-orange mimetite balls, and the Chah-Khouni and Kale-Kafi mines, located about 40 km east-southeast of Nakhlak, have produced orange to yellow, tabular to pyramidal wulfenite crystals up to 3 cm on edge (Minrec 54.3.383-408).

At the Erupcion-Ahumada mine, Los Lamentos, Chihuahua, Mexico, wulfenite occurs on a massive limestone matrix, and a boulder of calcite covered with wulfenite crystals has been found there. Pseudomorphs of vanadinite after wulfenite have also been found, as well as vanadinite on hemimorphite that has replaced wulfenite (R&M 94.1.40-41, 58).

At the Apex mine, San Carlos, Manuel Benavides, Chihuahua, Mexico, wulfenite is found on dolomite (R&M 94.1.38).

At the Ojuela mine, Mapimi, Mexico, wulfenite is associated with mimetite and mottramite, and some specimens have calcite crystals perched on them. Pseudomorphs of quartz after wulfenite, associated with smithsonite have been found here, as well as pseudomorphs of duftite after wulfenite associated with calcite, mimetite and goethite (R&M 94.1.36-37, 58).

At the San Francisco mine, Rancho Cerro Prieto, Near Cucurpe, Sonora, Mexico, wulfenite is associated with mimetite and may be replaced by it, forming pseudomorphs of mimetite after wulfenite (R&M 94.1.43-44, 58, KL p28).

At the Tsumeb mine, Namibia, pseudomorphs of bayldonite, conichalcite, dolomite, malachite, smithsonite, stolzite, mottramite and duftite after wulfenite have been found, but they are extremely rare (R&M 94.1.54-59, KL p203). Pseudomorphs of wulfenite after anglesite have also been found here (KL p216). Wulfenite has been found as an encrustation on the termination of a crystal of an arsentsumebite (or possibly bayldonite) replacement after mimetite (R&M 94.1.71-72). Very common associates are calcite, dolomite, duftite, malachite and mimetite. Moderately common associates are azurite, cerussite, dioptase, goethite, hematite, mottramite, quartz and smithsonite. Rare or very rare associates are adamite, alamosite, anglesite, aragonite, arsentsumebite, bayldonite, beudantite, biehlite, conichalcite, copper, cuprite, devilline, feinglosite, kaolinite, kegelite, leadhillite, lukrahnite, molybdofornacite, olivenite, rhodochrosite, rosasite, scorodite, serpierite, tenorite, tsumcorite, willemite, zincgartrellite and zincolivenite (R&M 94.1.77).
Two commonly observed parageneses for wulfenite are:
goethite > wulfenite > mimetite > malachite, and
(hematite plus goethite) > wulfenite (i) > duftite > wulfenite (ii)
A third, rare paragenesis is:
primary sulphides > wulfenite > alamosite > kegelite > leadhillite > cerussite
(R&M 94.1.78).

At the Sachaverel farm, Winster, Derbyshire, England, UK, wulfenite is associated with pyromorphite, galena and fluorite (RES p109).

At Breedon quarry, Breedon on the Hill, Leicestershire, England, UK, wulfenite is associated with galena and cerussite (RES p203).

At Roar Hill, Ballater, Buchan Grampian, Scotland, UK, lead-bearing vein mineralisation was exposed during recent work carried out on an unmetalled vehicle track. A small temporary quarry exposed fluorite-bearing quartz veins and minor wulfenite in light-coloured granite. At a second site, a little further to the west, an oxidised galena-bearing quartz vein was exposed.
Near end-member wulfenite was identified by X-ray diffraction in vein quartz at both locations. At the quarry exposure it occurs as bright orange to red tabular to bipyramidal crystals, easily visible to the naked eye, covering areas of colourless to smoky quartz matrix up to 6 mm across. Similar specimens were found at the track exposure, where wulfenite is commonly associated with pyromorphite (JRS 22.30-37).

In Arizona, USA, wulfenite crystals may be coated by younger minerals, frequently quartz, calcite and second generation wulfenite (R&M 94.1.12).

At the Hilltop mine, Cochise county, Arizona, USA, wulfenite often occurs on calcite (R&M 94.1.18).

At the Silver Bill-Mystery mine, Cochise county, Arizona, USA, wulfenite commonly occurs with a coating of calcite (R&M 94.1.12).

At the Finch mine, Gila county, Arizona, USA, wulfenite typically occurs as crystals coated with a microcrystalline quartz druse. Pseudomorphs of quartz, hemimorphite, descloizite and vanadinite after wulfenite have also been found here, and associated minerals include calcite (R&M 94.1.14 and 57, KL p253).

At the 79 mine, Gila county, Arizona, USA, pseudomorphs of quartz and hemimorphite after wulfenite have been found (R&M 94.1.57).

At the Red Cloud mine, La Paz county, Arizona, USA, vanadinite pseudomorphs after wulfenite have been found (KL p209).

At the Total Wreck mine, Pima county, Arizona, USA, Pseudomorphs of
mottramite after wulfenite have been found (R&M 94.1.28, 58).

At the Childs-Adwinkle Mine, Copper Creek, Copper Creek, Pinal county, Arizona, USA, wulfenite occurs as well formed crystals to 1 mm associated with brochantite, libethenite, malachite and azurite (R&M 96.2.155-156).

At the Mammoth-St Anthony mine, Pinal county, Arizona, USA, wulfenite is sometimes associated with mimetite and other secondary minerals such as sauconite, dioptase and cerussite. Pseudomorphs of descloizite after wulfenite have been found here (R&M 94.1.18, 58).

At the Rowley mine, Maricopa county, Arizona, USA, wulfenite commonly occurs on a baryte matrix associated with mimetite (R&M 94.1.23). Pseudomorphs of vanadinite after wulfenite have been found here (R&M 94.1.28).

At the Glove mine, Santa Cruz county, Arizona, USA, wulfenite sometimes occurs with inclusions or coatings of manganese oxide minerals, or it may be replaced by them (R&M 94.1.14-18). Pseudomorphs of descloizite and mottramite after wulfenite have been found here (R&M 94.1.28).

At Trumbull, Connecticut, USA, wulfenite pseudomorphs after scheelite have been found (KL p217).

At the Red Cloud copper mine, Lincoln county, New Mexico, USA, wulfenite is associated with mottramite, vanadinite and mimetite (R&M 94.1.65).

At the Surprise mine, Luna county, New Mexico, USA, wulfenite has been found on galena that has been partially altered to cerussite (R&M 94.1.65, R&M 94.3.236-237).

From the Anira mine, Santa Fe county, New Mexico, USA, a specimen of massive wulfenite with minor iron gossan and calcite has been found (R&M 94.1.65).

At the Big Chief mine, Sierra county, New Mexico, USA, wulfenite has been found associated with vanadinite (R&M 94.1.65).

At the Macy mine, Sierra county, New Mexico, USA, wulfenite is found on limestone (R&M 94.1.62).

At the Petroglyph mine, Sierra county, New Mexico, USA, wulfenite is often coated with chalcedony (R&M 94.1.65).

From the Graphic mine, Socorro county, New Mexico, USA, a specimen has been found with wulfenite on malachite (R&M 94.1.63).

At the Lemitar mounains, Sorocco county, New Mexico, USA, wulfenite is often associated with fluorite and cerussite (R&M 94.1.65).

At the Mex-Tex and Blanchard mines, Socorro county, New Mexico, USA, some wulfenite pseudomorphs after galena have been found (R&M 94.1.64).

At the Ora tunnel and Hickey mine, Socorro county, New Mexico, USA, wulfenite has been found on baryte and fluorite, and associated with oxidised galena (R&M 94.1.64).

At the Kabwe mine, Central Province, Zambia, wulfenite is extremely rare, but it has been found in a cavity with quartz (R&M).

Back to Minerals