Wulfenite
Wulfenite is a rare secondary mineral and very beautiful gem. It is rare because crystals are usually small, tabular and thin. Beautifully colored gems have been faceted from intense orange and reddish orange crystals found at the Red Cloud Mine (and others) in Arizona. Some large, pale yellow gems have been faceted from crystals found at Tsumeb, Namibia. There are many other sources of the beautiful crystal specimens worldwide including Los Lomentos, Mexico; Poland; Yugoslavia; Austria, Czech Republic; Germany Morocco and Australia. A few of these locations have also produced faceted gems.
There are hundreds of localities for Wulfenite; a few for fine examples include: from Bleiberg, Carinthia, Austria. At Mežica (Mies) and Crna pri Prevaljah (Schwartzenbach), Slovenia. In the USA, from Arizona, at the Red Cloud and nearby mines, Silver district, La Paz County, in the Old Yuma mine, near Tucson, Pima County, at the Mammoth-St. Anthony mine, Tiger, Pinal County, large crystals from the Glove mine, near Amado, Tyndall district, Santa Cruz County, at the Hilltop mine, Chiricahua Mountains, and in the Defiance mine, Gleeson, Cochise County; in New Mexico, at the Stevenson-Bennett mine, Organ Mountains, Doña Ana County; in the Lucin District, Elko County, Nevada. In Mexico, from the San Francisco mine, Cerro Prieta, Magdalena, Sonora; at Los Lamentos and Santa Eulalia, Chihuahua; in the Ojuela mine, Mapimí, Durango. Large crystals at Tsumeb, Namibia. Ponderous crystals from Mfouati, Congo Republic. In the Tchah Kharboze mine, Anarak district, Iran. At the Touissit mine, near Oujda, Morocco. From Sidjak, Uzbekistan. At the Christmas mine, Chillago, Queensland, Australia.
| Chemical Formula: | PbMoO4 |
| Lead Molybdate | |
| Molecular Weight: | 367.14 gm |
| Composition: | Molybdenum | 26.13 % | Mo | 39.21 % | MoO3 |
| Lead | 56.44 % | Pb | 65.15 % | PbO2 | |
| Oxygen | 17.43 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Tetragonal – Dipyramidal |
| Crystal Habit: | Crystals commonly square, flat tabular on [001], showing {001} and flat or rounded vicinal faces, {010}, to 11 cm; may be elongated along [001], or pyramidal {011}. Commonly other {0kl}, {hkl} forms, some showing pyramidal hemihedrism; granular, massive. |
| Twinning: | On {001}, as contact twins, common. |
| Cleavage: | Distinct on {011}, indistinct on {001}, {013} |
| Fracture: | Sub-Conchoidal to Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 2.5 – 3.0 |
| Density: | 6.50 – 7.00 (g/cm3) |
| Luminescence: | Fluorescent; yellow to orange to red under SW UV and LW UV |
| Radioactivity: | Not Radioactive |
| Other: | Some individual crystals may be Piezoelectric. |
| Color: | Yellow, pale Yellow, Yellow-Orange, Orange, Red-Orange, Gray, rarely White, Colorless, Olive-Green, pale to dark Blue, Reddish Brown, Brown, Black. |
| Transparency: | Transparent, Translucent, Opaque |
| Luster: | Resinous, Subadamantine to Adamantine |
| Refractive Index: | 2.304 – 2.402 Uniaxial ( – ); may be anomalously Biaxial |
| Birefringence: | 0.980 |
| Dispersion: | Strong; (0.203) |
| Pleochroism: | Weak; orange and yellow |
