The Collaborative International Dictionary
Lithophyse
Lithophyse \Lith"o*physe\, n. [Litho- + Gr. ? a flatus, air bubble.] (Min.) A spherulitic cavity often with concentric chambers, observed in some volcanic rocks, as in rhyolitic lavas. It is supposed to be produced by expanding gas, whence the name.
Wiktionary
lithophyse
n. (context mineralogy English) A spherulitic cavity, often with concentric chambers, observed in some volcanic rocks, such as rhyolitic lavas.