chert
noun
- hard, fine-grained sedimentary rock composed of cryptocrystalline silica
Wiktionary
Pronunciation: /t͡ʃɜːt/ / /t͡ʃɝt/
noun
Etymology: Unknown.
- Massive, usually dull-colored and opaque, quartzite, hornstone, impure chalcedony, or other flint-like mineral.
- A flint-like tool made from chert.