Scorodite: Tsumeb, Namibia (1.15, 1.50)
Gems of scorodite are extremely rare (usually Tsumeb), but cut stones have a lovely color and intense pleochroism. Too soft to wear, the stone is suited for collectors of the rare and unusual.
Scorodite Value
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Scorodite Information
| Data | Value |
| Name | Scorodite |
| Is a Variety of | Variscite |
| Crystallography | Orthorhombic. Crystals pyramidal, tabular, prismatic; massive, crusts. |
| Colors | Pale grayish green, yellowish brown to brown, colorless, bluish green, blue, violet. |
| Luster | Vitreous to resinous. |
| Hardness | 3.5-4. |
| Density | 3.28-3.29. |
| Cleavage | Imperfect. Fracture subconchoidal. Brittle. |
| Stone Sizes | Cut gems are always small, mostly from Tsumeb material. The maximum to expect is about 5 carats but even this would be very large for the species. Smithsonian Institution (Washington, D.C): 2.6 (purplish, Namibia). |
| Luminescence | None. Soluble in HCl. |
| Spectral | One line at 4500, broad absorption in the green (Tsumeb). |
| Formula | FeAsO4 – 2H2O. |
| Pleochroism | Intense: purplish/bluish (Tsumeb). |
SCORODITE Series to Mansfieldite: AlAsO4 · 2H2O.
| Properties of Scorodite from Various Localities |
α |
β |
γ |
Birefringence |
2V |
| Durango, Mexico |
1.784 |
1.795 |
1.814 |
0.030 |
75° |
| Idaho |
1.738 |
1.742 |
1.765 |
0.027 |
60° |
| Oregon |
1.741 |
1.744 |
1.768 |
0.027 |
40° |
| Tsumeb, Namibia |
1.785 |
1.796 |
1.816 |
0.031 |
75°Optics: Biaxial (+), variable 2V. |
Occurrence: A secondary mineral resulting from the oxidation of arsenious ores.
Utah; South Dakota; California; Washington; Idaho;
Nevada; Wyoming.
Ontario, Canada; Japan; England.
Durango, Mexico; fine blue crystals.
Ouro Preto, Minas Gerais, Brazil: good crystals, some gemmy.
Tsumeb, Namibia: pleochroic blue crystals, to 25 mm long, some gemmy.
Comments: Gems of scorodite are extremely rare (usually Tsumeb), but cut stones have a lovely color and intense pleochroism. Too soft to wear, the stone is suited for collectors of the rare and unusual.
Name: From the Greek for garliclike because the material emits the typical garlic odor of arsenic when heated.
