Synadelphite et Diadelphite

Synadelphite and Diadelphite, Mossgruvan mine, Nordmark, Wermland, Sweden. In a barite gangue 6x4,5x4cm black grains of synadelphite, a very rare mineral, a hydroxy arsenate of manganese, magnesium, calcium and lead, associated with brown patches of diadelphite or hematolite, a hydroxy arsenate of manganese, magnesium and aluminium, also rare. Four historical and handwritten labels. Deyrolle, two by Chervet and one by the Marquis de Mauroy.