volcanic glass

noun

1. a natural glass produced when molten lava cools very rapidly; obsidian.

volcanic glass

noun

1. any of several glassy volcanic igneous rocks, such as obsidian and pitchstone

volcanic glass

1. Natural glass produced by the cooling of molten lava too quickly to permit crystallization. Obsidian is a type of volcanic glass.

Word History and Origins

Origin of volcanic glass¹

First recorded in 1830–40