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.
Biaxial (+), variable 2V. See "Identifying Characteristics" 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-170221,” Alto das Quelhas do Gestoso Mines, Gestoso, Manhouce, São Pedro do Sul, Viseu District, Portugal. Picture width 1.5 mm. Collection and photograph Christian Rewitzer. Licensed under CC By-SA 3.0.
Comments
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).
Although not a rare mineral, faceted 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, faceted pieces would make interesting collector’s gems rather than practical jewelry stones.
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.
Optical Properties of Scorodite from Various Localities
Consumers may encounter so-called “scorolites” for sale online. Often marketed as “scorolite opals,” they are, in fact, simulants, usually purplish glass or quartz pieces. Occasionally, you might encounter this same material offered as scorodite. Keep in mind that “scorolite” is not a synonym or alternate name for scorodite. Quartz and glass are distinct gemologically from scorodites. (This confusion may stem from a typo in a paper on geo-environmental hazards in groundwater in India).
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.
Scorodites just don’t have the wearability to serve as jewelry stones. Furthermore, they’re soluble in acids and contain arsenic. While this shouldn’t pose a problem for wear or display, gem cutters should take precautions to prevent inhaling particles, protect their eyes, and wash their hands while working with scorodites.