“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. |
| 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 |
| Luster | Submetallic to resinous. |
| Hardness | 4 - 4.5 (increases with iron content). |
| Fracture | Uneven |
| Specific Gravity | 7.12-7.18 (increases with iron content). |
| Birefringence | 0.13. |
| 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. |
| Luminescence | None. |
| Luminescence Present | No |
| Transparency | Transparent to opaque. |
| Absorption Spectrum | Not diagnostic. |
| Phenomena | Iridescence. |
| Formula |
MnWO4 Series to Ferberite: FeWO4. |
| 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 + |
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.
IGS Newsletter