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fool's gold

American  

noun

  1. iron or copper pyrites, sometimes mistaken for gold.

fool's gold British  

noun

  1. any of various yellow minerals, esp pyrite or chalcopyrite, that can be mistaken for gold

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
fool's gold Scientific  
/ fo̅o̅lz /

  1. Any of several minerals, especially pyrite and chalcopyrite, sometimes mistaken for gold.

Etymology

Origin of fool's gold

An Americanism dating back to 1870–75

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.