spherulite

A small, usually spheroidal body consisting of radiating crystals, found in obsidian and other glassy lava rocks.

A vitreous globule, such as those of which perlite is made up, having a more or loss perfectly developed concentric and at the same time decidedly radiating fibrous structure. The highly silicious volcanic rocks not unfrequently have a spherulitic structure.

Same as radiolite, 2.

A minute spherical crystalline body having a radiated structure, observed in some vitreous volcanic rocks, as obsidian and pearlstone.

a minute spherical crystalline body having a radiated structure, observed in some vitreous volcanic rocks, as obsidian and pearlstone.