“Hubnerite With Quartz,” Pasto Bueno, Pallasca Province, Ancash Dept., Peru. © Rob Lavinsky, www.iRocks.com. Used with permission.
It should not be difficult to find numerous small, faceted huebnerite gems (also hübnerite or hubnerite) among larger collections. Certainly ample material exists to cut a number of such gems, although they are rarely offered for sale.
| Data | Value |
|---|---|
| Name | Huebnerite (Hübnerite) |
| Colors | Brownish black, yellowish to reddish brown, red. Sometimes color banded; sometimes tarnished iridescent. |
| Hardness | 4 - 4.5 (increases with iron content). |
| Fracture | Uneven |
| Cleavage | Perfect in 1 direction |
| Stone Sizes | Huebnerite is transparent, and opacity increases with iron content. Material suitable for faceting occurs in Peru, and stones of several carats in weight may be cut but tend to be dark. |
| Formula | MnWO4 Series to Ferberite: FeWO4. |
| Crystallography | Monoclinic; crystals prismatic; flattened; tabular, often striated in direction of elongation. Often in crystal groups, radiating or parallel aggregates. Commonly twinned. |
| Refractive Index | 2.17-2.32 |
| Birefringence | 0.13. |
| Luminescence | None. |
| Luminescence Present | No |
| Absorption Spectrum | Not diagnostic. |
| Pleochroism | Varies with locality and iron content: bright yellow/orange-red/orange-red; greenish-yellow/orange-red/bright red; olive green/brick-red/dark red. |
| Optics | a = 2.17-2.20; β = 2.22; γ = 2.30-2.32. Biaxial (+). |
| Optic Sign | Biaxial + |
| Luster | Submetallic to resinous. |
| Specific Gravity | 7.12-7.18 (increases with iron content). |
| Transparency | Transparent to opaque. |
| Phenomena | Iridescence. |
Optics: a = 2.17-2.20; β= 2.22; γ= 2.30-2.32. Biaxial (+).
Streak: yellowish, reddish brown, blackish to greenish gray.
Occurrence: High-temperature hydrothermal ore veins; quartz veins in or near granitic rocks; Many localities in western United States (Colorado: Idaho; Nevada; New Mexico; Arizona; South Dakota).
France; Czechoslovakia; Australia.
Pasto Bueno, Peru: transparent crystals.
Comments: It should not be difficult to find numerous small faceted huebnerites among larger gemstone collections. Certainly ample material exists to cut a number of such gems, although they are rarely offered for sale.
Name: After Adolph Hubner, a metallurgist from Freiburg, Saxony (Germany). Ferberite was named after Rudolph Ferber, of Gera, Germany.
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