Sewardite [SEP] named after
Sewardite
Sewardite is a rare arsenate mineral with formula of CaFe(AsO)(OH). Sewardite was discovered in 1982 and named for the mineralogist, Terry M. Seward (born 1940), a professor of geochemistry in Zürich, Switzerland.
Properties.
Sewardite is orthorhombic, which means in crystallographic terms, it contains 3 axes of unequal length, one "c" axis, and 1 "a" axis, and 1 "b" axis. The "c" axis runs vertically, and the "b" axis forms a
Carminite
Carminite (PbFe(AsO)(OH)) is an anhydrous arsenate mineral containing hydroxyl. It is a rare secondary mineral that is structurally related to palermoite (LiSrAl(PO)(OH)). Sewardite (CaFe(AsO)(OH)) is an analogue of carminite, with calcium in sewardite in place of the lead in carminite. Mawbyite is a dimorph (same formula, different structure) of carminite; mawbyite is monoclinic and carminite is orthorhombic. It has a molar mass of 639.87 g. It was discovered in 1850 and named for the characteristic carmine colour.
Structure