Erythrite is just a beautifully bright red-purple mineral that is colored as “cobalt bloom” by miners because it is extremely noticable and had been used to identify veins of cobalt-bearing ore. This is a weathering product of cobalt containing minerals such as for example Cobaltite. Most Erythrite is found in the form of crusts, but larger crystals are found at mines in the Bou Azzer region of Morocco. Erythrite gems are very rare and difficult to cut because of its very soft nature (Mohs 1.5 – 2.5) and cleavage that is perfect.

There are many localities for finding Erythrite, but number of value. In France, at Chalanches, near Allemont, Isère. In Germany, fine examples with large crystals from Schneeberg, Saxony, at Wittichen, Black Forest, from Richelsdorf, Hesse, and elsewhere. At Jáchymov (Joachimsthal), Czech Republic. Within the Botallack mine, St. Just, and from a true quantity of other areas in Cornwall, England. Larger crystals from the Aghbar (Arhbar), Irhtem (Ightem), and other mines in the Bou Azzer district, Morocco. From Cobalt, Ontario, Canada. Within the United States Of America, at the Blackbird mine, Lemhi County, Idaho. From the Sara Alicia mine, near Alamos, Sonora, Mexico. In Australia, from Mt. Cobalt, 110 kilometer south of Cloncurry, Queensland, and at the Dome Rock copper mine, about 40 km northwest of Mingary, South Australia.

Category: Arsenate mineral
Vivianite group
Chemical Formula: Co3(AsO4)2 • 8(H2O)
Hydrated Cobalt Arsenate
Molecular Weight: 598.76 gm
Composition: Cobalt 29.53 % Co 41.55 % Co2O3
Arsenic 25.03 % As 38.39 % As2O5
Hydrogen 2.69 % H 24.07 % H2O
Oxygen 42.75 % O


Crystallography: Monoclinic – Prismatic
Crystal Habit: Rarely well crystallized, typically flattened on [010], may be elongated prismatic and striated || [001], with many forms, to 10 cm. In radial or stellate aggregates, fibrous, drusy; usually powdery, massive.
Twinning: None


Cleavage: Perfect on {010}; Poor on {100} and {102}
Fracture: Conchoidal to Irregular/Uneven
Tenacity: Sectile, flexible in thin {010} laminae
Moh’s Hardness: 1.5 – 2.5
Density: 3.06 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive
Other: Soluble in acids.


Color: Crimson to Peach-Red, pale Rose, or Pink, may be zoned.
Transparency: Transparent to Translucent
Luster: Sub-Adamantine, Pearly on {010} cleavages; Dull to Earthy as aggregates or massive
Refractive Index: 1.626 – 1.701  Biaxial  ( + ); may be Biaxial  ( – )
Birefringence: 0.0730
Dispersion: r > v
Pleochroism: Visible; X = pale pinkish to pale rose; Y = pale violet to pale violet-rose; Z = deep red.