WULFENITE: Tsumeb, Namibia (21+)
The red of wulfenite, especially from the Red Cloud Mine in Arizona, is one of the richest colors in nature. Specimens of wulfenite are esthetically magnificent and are greatly prized by collectors. The crystal habit is tabular and the individual crystals are usually very thin, making it difficult to find a suitable cutting fragment. Gems are then difficult to cut because of the softness of the material and its sensitivity to heat and vibration. These characteristics make wulfenite totally unsuited for jewelry, but it makes a spectacular collector gem of great rarity. A red wulfenite over 1 carat is extremely scarce, likewise a yellowish or orange one over 1-2 carats. The only larger stones come from Tsumeb material, but the facetable crystals from this locality were extremely uncommon and very few stones have been cut from them.
Wulfenite Value
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Wulfenite Information
| Data | Value |
| Name | Wulfenite |
| Crystallography | Tetragonal. Crystals commonly tabular with square outline; also pyramidal; massive, granular. |
| Colors | Orange, (various shades), brownish orange, yellow, brownish yellow, yellow-orange, red, brown, yellowish gray, tan, greenish brown. |
| Luster | Resinous to adamantine. |
| Hardness | 2.5-3 |
| Density | 6.5-7.0 |
| Birefringence | 0.122 |
| Cleavage | Distinct 1 direction. Fracture uneven to subconchoidal. Brittle. |
| Dispersion | 0.203 |
| Stone Sizes | Most wulfenite crystals, especially those from U.S. localities, are too thin for the cutting of gemstones. However, an occasional crystal is both thick and transparent enough for faceting, notably from the Red Cloud Mine, the Seventynine Mine, and others. Some of these have yielded gems up to about 5 carats. Tsumeb, Namibia, has produced wulfenite crystals several inches across, from which gems up to 50 carats have been faceted. Smithsonian Institution (Washington, D.C): 46.1, 15.7, 9.6 (pale yellow, Tsumeb); 10+ (orange, Los Lomentos, Mexico). Private Collection: 54 (yellow, Tsumeb). Devonian Group (Calgary, Alberta, Canada): 15.25 (yellow, Tsumeb); 9.44 (red, Arizona). |
| Luminescence | None. |
| Spectral | Not diagnostic. |
| Formula | PbMoO4. |
| Pleochroism | Weak, in orange to yellow tints. |
Optics: o= 2.405; e=2.283.
Uniaxial (-).
Occurrence: Secondary mineral in the oxidized zone of ore deposits.
Arizona (Glove Mine, Rowley Mine, Red Cloud Mine, Mammoth Mine, others); New Mexico: Nevada: Utah; Wheatley Mines, Chester, Pennsylvania; Loudville, Massachusetts.
Mexico: Lox Lomentos, many other locations; Poland; Yugoslavia; Austria; Czechoslovakia: Germany; Sardinia; Algeria; Morocco; Australia.
Tsumeb, Namibia: yellowish tan crystals up to 5 inches on edge, some facetable.
WULFENITE: Arizona (gem ~1.5, crystal 1 inch long, Red Cloud Mine)
Comments: The red of wulfenite, especially from the Red Cloud Mine in Arizona, is one of the richest colors in nature. Specimens of wulfenite are esthetically magnificent and are greatly prized by collectors. The crystal habit is tabular and the individual crystals are usually very thin, making it difficult to find a suitable cutting fragment. Gems are then difficult to cut because of the softness of the material and its sensitivity to heat and vibration. These characteristics make wulfenite totally unsuited for jewelry, but it makes a spectacular collector gem of great rarity. A red wulfenite over 1 carat is extremely scarce, likewise a yellowish or orange one over 1-2 carats. The only larger stones come from Tsumeb material, but the facetable crystals from this locality were extremely uncommon and very few stones have been cut from them.
Name: After the Austrian mineralogist, Franz Xavier Wulfen, who wrote a lengthy monograph in 1785 on the lead ores of Carinthia.
