Scorodite: Tsumeb, Namibia (1.0). Photo © Joel E. Arem, PhD, FGA. Used with permission.
With lovely colors and intense pleochroism, faceted scorodite is a prize for collectors of the rare and unusual. However, it’s too soft for jewelry use.
Scorodite: Tsumeb, Namibia (1.0). Photo © Joel E. Arem, PhD, FGA. Used with permission.
With lovely colors and intense pleochroism, faceted scorodite is a prize for collectors of the rare and unusual. However, it’s too soft for jewelry use.
| Data | Value |
|---|---|
| Name | Scorodite |
| Is a Variety of | Variscite |
| Crystallography | Orthorhombic. Crystals pyramidal, tabular, prismatic; massive, crusts. |
| Crystallographic Forms | |
| Refractive Index | Varies by locality, 1.738-1.816. See "Identifying Scorodites" below. |
| Colors | Pale grayish green, yellowish brown to brown, colorless, blueish green, blue, violet. |
| Luster | Vitreous to resinous |
| Hardness | 3.5-4 |
| Fracture | Subconchoidal |
| Specific Gravity | 3.28-3.29 |
| Birefringence | Varies by locality, 0.027-0.031. See "Identifying Scorodites" below. |
| Cleavage | Imperfect |
| Dispersion | Relatively strong |
| Luminescence | None |
| Luminescence Present | No |
| Transparency | Translucent to semi-transparent |
| Absorption Spectrum | One line at 4500, broad absorption in the green (Tsumeb). |
| Phenomena | Color change (very rare) |
| Formula | Fe3+AsO4 · 2H2O |
| Pleochroism | Intense: purplish/bluish (Tsumeb). |
| Optics | Biaxial (+), variable 2V. See "Identifying Scorodites" below. |
| Optic Sign | Biaxial + |
| Etymology | From the Greek skorodon for “garlic,” because the material emits the typical garlic odor of arsenic when heated. |
| Occurrence | A secondary mineral resulting from the oxidation of arsenious ores. |
Scorodite crystal, Alto das Quelhas do Gestoso Mines, Gestoso, Manhouce, São Pedro do Sul, Viseu District, Portugal. Picture width 1.5 mm. Collection and photograph of Christian Rewitzer. Licensed under CC By-SA 3.0.
Scorodite belongs to the variscite mineral group. It forms series as the ferric iron analogue (Fe3+) with mansfieldite (AlAsO4 · 2H2O), yanomamite (InAsO4 · 2H2O), and strengite (FePO4 · 2H2O). These minerals occur far more rarely than their fellow series member scorodite. Accordingly, faceted examples of these minerals are even rarer than faceted scorodites.
Pear-cut mansfieldite, 2.99 cts, 12.6 x 7.8 mm, Algeria. © Rob Lavinsky, www.iRocks.com. Used with permission. (Images combined to show details).
Although not a rare mineral in nature, faceted or cabbed scorodites are extremely rare. A low Mohs hardness score of 3.5 to 4 and imperfect cleavage make them very susceptible to scratches and blows. Thus, scorodites just don’t have the wearability to serve as jewelry stones. Furthermore, they’re soluble in acids and contain arsenic. Gem cutters should take precautions to prevent inhaling particles, protect their eyes, and wash their hands while working with scorodites.
Since such a soft stone can be scratched easily, which can release small particles of the gem, jewelry use is not recommended. Reserve scorodites for display in mineral or gem collections.
Oval cabbed scorodite, 5.18 cts, 11.8 x 9.5 mm, Morocco. © The Gem Trader. Used with permission.
Rare specimens display color change, from blue-green in daylight to blueish purple or grayish blue in incandescent light.
Scorodites may have a greenish-white streak. Please note that streak testing may harm or destroy your specimen. Conduct it on a piece of rough, never a finished gem, only as a last resort.
|
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° |
Scientists have synthesized scorodite, including crystals, for research into the safe disposal of arsenic. However, there is no known jewelry use of this material.
Consumers may encounter so-called “scorolites” for sale online, especially as purplish beads. Occasionally, these same pieces are offered as a type of scorodite. More often, they’re marketed as “scorolite opals.” However, in fact, they’re simulants, usually purplish glass or quartz pieces. Of course, quartz and glass are distinct gemologically from opals and scorodites. Gemologists can readily distinguish these materials.
“Scorolite” is not an accepted synonym or trade name for scorodite. This confusion may stem from a typo in a paper on geo-environmental hazards in groundwater in India. Any gems sold as “scorolites” should come with a disclaimer identifying what they actually are.
“Scorolite” rondelles. Photo courtesy of liveauctioneers.com and Blue Antiques Blue.
There are no known gemstone enhancements for scorodites.
Tsumeb, Namibia produces beautiful, pleochroic blue/purplish crystals, some gemmy, up to 25 mm long.
Durango, Mexico and Ouro Preto, Minas Gerais, Brazil also yield fine, blue crystals, some gemmy.
Other notable crystal sources include
An unusual stalactitic growth of scorodites. 7.7 x 6.2 x 1.0 cm, Djebel Debar, Hamman, Meskhootine, Constantine Province, Algeria. © Rob Lavinsky, www.iRocks.com. Used with permission.
Scorodites almost always make small faceted gems. As a reasonable maximum, expect about five carats. However, even that would be very large for the species.
Clean scorodites with a soft brush, mild detergent, and warm water. For more care recommendations, consult our gemstone jewelry care guide.
Scorodites: Tsumeb, Namibia (1.15, 1.50). Photo © Joel E. Arem, PhD, FGA. Used with permission.
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