Annabergite

  Annabergite is a mineral consisting of a hydrous nickel arsenate, Ni₃(AsO₄)₂·8H₂O, crystallizing in the monoclinic system and isomorphous with vivianite and erythrite. Crystals are minute and capillary and rarely met with, the mineral occurring usually as soft earthy masses and encrustations. A fine apple-green colour is its characteristic feature. It was long known (since 1758) under the name nickel ochre; the name annabergite was proposed by H. J. Brooke and W H. Miller in 1852, from Annaberg in Saxony, one of the localities of the mineral. It occurs with ores of nickel, of which it is a product of alteration. A variety, from Creetown in Kirkcudbrightshire, in which a portion of the nickel is replaced by calcium, has been called dudgeonite, after P. Dudgeon, who found it.

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Closely related is cabrerite wherein some of the nickel is replaced by magnesium. It is named for Sierra Cabrera in Spain where it was originally found.

References

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.