WebSpherulites are formed during the process of devitrification in obsidian due to the influence of hydrothermal fluids. During devitrification, the glass crystallizes slowly to form Spherulites are most common in silica-rich glassy rocks. Sometimes they compose the whole mass; more usually they are surrounded by a glassy or felsitic base. When obsidians are devitrified, the spherulites are often traceable, though they may be more or less completely recrystallized or silicified. In the center of a … Zobraziť viac In petrology, spherulites 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 … Zobraziť viac Under the microscope the spherulites are of circular outline and are composed of thin divergent fibers that are crystalline as verified with polarized light. Between crossed Zobraziť viac Very large and cavernous spherulites are called lithophysae; they are found in obsidians at Lipari, in Yellowstone Park and other places. The characteristic radiate fibrous structure … Zobraziť viac Variolites are a type of radiate fibrous growth, resembling spherulites in many respects, consisting of minute feathery crystals spreading outwards through a fine grained or glassy rock. In variolites there are straight or feathery feldspar crystals (usually Zobraziť viac Occasionally spherulites are found that are many centimeters and, even more rarely, up to two or three meters in diameter. Those … Zobraziť viac Artificial glass sometimes crystallizes and contains spherulites that may be as large as a marble. As the glass has little similarity in chemical composition to volcanic … Zobraziť viac
Igneous Rocks Volume N . 1; Composition, Texture and Cl…
Web1. nov 2008 · We measured water concentration profiles around spherulites in obsidian by synchrotron Fourier transform infrared spectroscopy. The distribution of OH - groups … http://www.alexstrekeisen.it/english/vulc/spherulites.php punch back twice as hard
Spherulite formation in obsidian lavas in the Aeolian Islands, Italy
Web22. jún 2009 · spherulites. The next order of crystallization in the obsidian is the spherulitic. The simplest and smallest as well as the first formed spherulites appear as minute, … Web1. nov 2008 · The transformation of obsidian to perlite and pitchstone is due to the metastability of volcanic glass relative to the crystalline state. These structures are not … WebSpherulites Spherulitic aggregate (pherulites) are radiating arrays of fibrous, needle-like or acicular, crystals that are common in glassy felsic volcanic rocks. Early descriptions of spherulites are by Cross and Iddings in 1891 … punch a wall