Erythrite


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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 ?
Here the presence of erythrite gives the first sign of cobalt mineralization.
The mineralogical fame of the Bou Azzer district is founded on its extensive suite of rare and colorful arsenates, and especially on its superlative macro-specimens of erythrite, roselite, roselitebeta and wendwilsonite.
Erythrite from Veins 7/5, Bou Azzer (2000-2001): deep red tabular crystals to more than 3.
Erythrite from Oumlil and Agoudal (2005): metallic-violet-red tabular and acicular crystals, some more than 2 cm, associated with sphaerocobaltite, the latter as carmine-red rhombohedral crystals to 1 mm.
Associations include erythrite, annabergite, talmes-site, powellite, galena and native gold.
01 mm, associated with erythrite, pharmacolite, lollingite, bluish green mcguinessite, talc and hematite on coarsely cleavable dolomite.
A dark variety appears in Vein 52, Ait Ahmane, with lollingite and fibrous erythrite.
In many cases the fissures are coated by newly formed erythrite and by countless octahedral crystals of arsenolite in colorless, white, or pale violet colors with a diamond-like brilliance.
In early 2002, at Aghbar, a dolomite boulder enriched in sulfides and shot through with erythrite was found.
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
Several good Moroccan erythrite specimens and one very good roselite were also available.
Francois and Christine also had erythrite from the new find, including a beautiful miniature 3 x 5 cm, with 2.