the GNU version of the Collaborative International Dictionary of English
n. A name given to a number of metallic minerals, sulphides of iron, copper, cobalt, nickel, and tin, of a white or yellowish color.
The Century Dictionary and Cyclopedia
n. Either of the common sulphids of iron, pyrite and marcasite, but also the yellow sulphid of copper and iron, chalcopyrite: the former are called distinctively iron pyrites, while the latter is known as copper pyrites.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. any of various metallic-looking sulfides (of which pyrite is the commonest)
Word Usage
"_Copperas: _ (Sulphate of iron or green vitriol,) a bright green mineral substance, formed by the decomposition of a peculiar ore of iron called pyrites, which is a sulphuret of iron."