py ‧ ri ‧ tes /paɪˈraɪtiːz $ pə-/ BrE AmE noun [uncountable]
[ Date: 1500-1600 ; Language: Latin ; Origin: 'flint' , from Greek , 'of or in fire' , from pyr ; ⇨ ↑ pyre ]
a mix of ↑ sulphur with a type of metal, usually iron, or iron and ↑ copper ⇨ fool’s gold :
iron pyrites