2 Answers

http://pubs.acs.org/doi/abs/10.1021/cg901460g

Spherulite

From Wikipedia, the free encyclopedia

Jump to: navigation, search

This article is about lithology. For other uses, see spherulite (polymer physics).

Spherulites in rhyolitic ash, Hailstone Trail, Echo Canyon, Chiricahua Mountains, Arizona.

Spherulite markings on this snowflake obsidian

Photomicrograph of rhyolite showing spherulitic texture (brown, between grey to white crystals).

In petrology, spherulites /?sf?r?la?t/ 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