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Download hereGENERAL DESCRIPTION
Erythrite is an hydrated cobalt arsenate, formed by the oxidation of cobalt arsenides and sulfo-arsenides. It forms a series with annabergite (hydrated nickel arseniate, Ni3(AsO4)2, 8H2O).
Translucent to transparent and with a vitreous lustre, crystals do not exceed a few centimetres. Rarely crystallized, they are prismatic, often acicular, flattened and striated.
It is not an important cobalt ore economically speaking but it is a very good indicator of the presence of cobalt deposits. With a pink to a very sharp red color, erythrite is highly appreciated by the collectors.
The most beautiful crystals come from the vein 7 of the district of Bou-Azzer (Morocco) where some crystals measure up to 5 cm and in the district of Schneeberg (Germany), where one finds very beautiful "flowers of crystals".
In France, it is present at Chalanches (Allemont, Isère), in the Cap Garonne (Var), in Giromagny (Territoire de Belfort), in Rabejec (Lodève), in the valley of Aure (Hautes-Pyrénées) and in many mines of Sainte Marie aux Mines (Vosges) like in various other mines of the Val de Villé (such as Urbeis) and Thann (Fanny mine).
The place of conservation of the type of this species is unknown.
Did you know? Erythrite was used for the preparation of pigments and the colour of glasses in dark blue ("blue of Chartres").
HISTORY : Name inspired from the Greek word "ερυθροσ" [erythros] meaning red, name given in reference to its colour
First described in 1832 par François-Sulpice Beudant (1787-1850), French mineralogist
Type-locality : Mines of the Challanches, Allemont, Isère and Richelse, Hesse-Nassau, Germany
ANCIENT NAME : Mine de cobalt en efflorescence, fleur de cobalt
CHEMICAL FORMULA : Co3 (AsO4)2 8H2O
CRYSTAL SYSTEM : Monoclinic
COLOR : Pink, red, pale pink, violett
DIAPHANIETY : Transparent to translucent
LUSTER : Adamantine, pearly
STREAK : Rose to pale red
MORPHOLOGIE : Seldmoly well crystallised. Elongated crystals, prismatic and striated, forming aggregates, massive, fibrous
HARDNESS : 1,5-2,5
CHEMICAL CLASS: 3,135
DENSITY : VII - Phosphates, arsenates and vanadates
GROUP : Vivianite
STRUNZ CLASS BEFORE 2001 : 7/C.13-70
STRUNZ CLASS AFTER 2001 : 8.CE.40
