The Collaborative International Dictionary
clinkstone
Phonolite \Pho"no*lite\, n. [Phono- + -lite: cf. F. phonolithe.] (Min.) A compact, feldspathic, igneous rock containing nephelite, ha["u]ynite, etc. Thin slabs give a ringing sound when struck; -- called also clinkstone.
Wiktionary
clinkstone
n. phonolite