describe how volcanic glass forms. what rock is volcanic glass?
Noun. 1. volcanic glass-a kind of natural glass produced when molten lava cools very rapidly. obsidian-acid or granitic glass formed by the rapid cooling of lava without crystallization; usually dark, but transparent in thin pieces. pitchstone-dark acid granitic glass. tachylite-a basic or basalt glass.
Width of sample 11 cm. Volcanic glass is an igneous rock that is composed of largely uncrystallized magmatic material. Most of it is not crystallized because the crystals had two difficult problems which restricted their growth. The first one is time.