Andradite

Andradite is a mineral species of the garnet group. It is a nesosilicate, with chemical formula Ca3Fe2Si3O12. Andradite includes four varieties: Colophonite: a historical variety found in the Scandinavian islands, brownish or reddish in color, often opaque or translucent. Demantoid: Vivid green in color, one of the most valuable and rare stones in the gemological world. Melanite: Black in color due to limited substitution of titanium for iron. Also known as "titanian andradite". Forms a solid solution with morimotoite and schorlomite depending on titanium and iron content. Topazolite: Yellow-green in color and sometimes of high enough quality to be cut into a faceted gemstone, it is rarer than demantoid. It was first described in 1868 for an occurrence in Drammen, Buskerud, Norway. Andradite was named after the Brazilian statesman, naturalist, professor and poet José Bonifácio de Andrada e Silva (1763–1838).

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