Main Entry: chert

Pronunciation: \ˈchərt, ˈchat\

Function: noun

Etymology: origin unknown

Date: 1679

: a rock resembling flint and consisting essentially of a large amount of fibrous chalcedony with smaller amounts of cryptocrystalline quartz and amorphous silica

— cherty \ˈchər-tē, ˈcha-\ adjective