Fool's gold is a substance that is found in rock and that looks very like gold.
2. uncountable noun
If you say that a plan for getting money is fool's gold, you mean that it is foolish to carry it out because you are sure that it will fail or cause problems.
[disapproval]
The British establishment seems to be off on another quest for fool's gold.
fool's gold in British English
noun
any of various yellow minerals, esp pyrite or chalcopyrite, that can be mistaken for gold
fool's gold in American English
US
pyrite or chalcopyrite, both of which resemble gold in color
fool's gold
a plan for making money that is foolish and sure to fail
The Chancellor dismissed as `pure fool's gold' the idea that devaluing the poundcould assist the British economy.