Spherulite

Spherulite

In petrology, spherulites /ˈsfɛrʊlaɪt/ are small, rounded bodies that commonly occur in vitreous igneous rocks. They are often visible in specimens of obsidian, pitchstone and rhyolite as globules about the size of millet seed or rice grain, with a duller luster than the surrounding glassy base of the rock, and when they are examined with a lens they prove to have a radiate fibrous structure.

Read more about Spherulite:  Structure, Occurrence, Megaspherulites, Lithophysae, Artificial Glass, Geometric Forms, Variolites

Other articles related to "spherulite, spherulites":

Spherulite - Variolites
... Another group of radiate fibrous growths resembling spherulites in many respects consists of minute feathery crystals spreading outwards through a fine grained or glassy rock ... oligoclase) forming pale colored spherulites a quarter to half an inch in diameter ...