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Webster 1913 Edition

Noun.

[Cf. F.

sphérulite

(Min.)

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

Noun.

A variety of obsidian or pearl-stone, found in rounded grains.

spherulite ‎(plural spherulites)

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