Erythrite


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Erythrite: Annabergite

erythrite

[′er·ə‚thrīt]
(mineralogy)
Co3(AsO4)2·82O A crimson, peach, or pink-red secondary oxidized cobalt mineral that occurs in monoclinic crystals, in globular and reniform masses, or in earthy forms. Also known as cobalt bloom; cobalt ocher; erythrine; peachblossom ore; red cobalt.
(organic chemistry)

Erythrite

 

(also cobalt bloom), an arsenate mineral, with the chemical composition C03[As04]-8H2O. Nickel substitutes iso-morphically for cobalt; admixtures of zinc, magnesium, and iron are also observed. Erythrite crystallizes in the monoclinic system. It is encountered primarily in the form of crusts, concretions, and earthy aggregates. Its color is pinkish red; with increasing nickel content, the color gradually changes to pale pink and gray and then to apple green, which is characteristic of the nickel arsenate annabergite, Ni3[AsO4] · 8H20, which is similar in structure to erythrite but occurs less frequently. Erythrite has a hardness of 1.5–2.5 on Mohs’ scale and a density of 3,100 kg/m3.

Erythrite is the product of the weathering of cobalt and nickelcobalt arsenides and sulfoarsenides. Upon oxidation, it is altered to black-colored hydroxides of trivalent cobalt (heterogenites). Its bright color is an important prospecting guide to the presence of arsenic ores of cobalt and nickel.

References in periodicals archive ?
Bouazzerite comes from Vein 7 in the Bou Azzer mine--the thick vein of ore which has produced the world's finest erythrite crystals (to 25 cm long!).
The mineral also appears near grains of copper sulfide and as chrysocolla pseudomorphs; associated species include conichalcite, lavendulan, annabergite and erythrite.
Cobaltite, one of the most recently formed cobalt sulfarsenides, occurs in minute octahedral crystals associated with erythrite in a safflorite vein.
Pinkish violet efflorescences of this species are widespread on old ore piles, commonly associated with other pink weathering products, chiefly erythrite. The cobaltkoritnigite is more violet-colored and the erythrite more pale pink to red.
By contrast to the ubiquitous erythrite, which is found in cavity zones and small veins everywhere in the district, cobaltkoritnigite is found preferentially--and never alone--in cavity zones which are rich in arsenolite.
With the ongoing development of the open-pit mine, cobaltlotharmeyerite has also been identified from a strongly oxidized ore zone rich in erythrite, associated with fine wendwilsonite crystals and with mansfieldite.
In the Mechoui deposit, conichalcite, with erythrite, forms transparent, smooth-surfaced spherules.
Erythrite [Co.sub.3](As[O.sub.4])[.sub.2] x 8[H.sub.2]O
Erythrite is the mineral which every collector automatically associates with Bou Azzer.
After many years during which no further noteworthy finds were made, Vein 7/5 at Bou Azzer began again in 2000 to produce outstanding specimens of erythrite, with deep violet crystals from 1 to 2 cm.
Because erythrite forms thin, leafy crystals and is very soft and non-elastic (like vivianite and gypsum), it is difficult to collect and transport without damage.
Erythrite is found everywhere in the Bou Azzer mining district.