ANNABERGITE  , a

mineral consisting of a hydrous nickel arsenate, Nia(AsO4)z+8HZO, 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 . (L . J .