Erythrite
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. |
