What is "sewardite"

n. (context mineralogy English) An orthorhombic-dipyramidal mineral containing arsenic, calcium, hydrogen, iron, oxygen, and zinc.

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.