Any of various yellowish or reddish-brown, crystalline
substances occurring in rocks and having the general
formula Mfe2O4
where M is some divalent metal, as
nickel, zinc etc.
One of the forms of pure metallic
iron, having high magnetic permeability and occurring
as a constituent of ordinary iron and steel. Any
of various compounds in which ferric oxide combines
with another metallic oxide, as calcium ferrite,
CaOFe2O3.
