Definition of "pyrite" [pyr•ite]

• A brass-colored mineral, FeS2, occurring widely and used as an iron ore and in producing sulfur dioxide for sulfuric acid. Also called fool's gold, iron pyrites. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Dr. HENNIGH: The fine sparkle you see is pyrite, which is fool's gold."
• "The process, termed pyrite oxidation, is enhanced when water moves through and over the surfaces of acid bearing rock exposed through mining activities which disturb the underlying geology."
• "The fossils are also rich in the mineral pyrite, which is the work of decomposing bacteria; again, this suggests that they were once living."