Spherulite — Spherulites, in petrology, 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… … Wikipedia
Crystallization of polymers — Spherulites viewed between crossed polarizers in an optical microscope. Crystallization of polymers is a process associated with partial alignment of their molecular chains. These chains fold together and form ordered regions called lamellae,… … Wikipedia
Tachylite — (also spelled tachylyte) is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt. It is a basic type of igneous rock that is decomposable by acids and readily fusible. The color is a… … Wikipedia
igneous rock — Any of various crystalline or glassy, noncrystalline rocks formed by the cooling and solidification of molten earth material (magma). Igneous rocks comprise one of the three principal classes of rocks, the others being metamorphic and sedimentary … Universalium
Microspherulite — Microspherulites are microscopic spherical particles with < 2 mm diameters, usually in the 100 micrometre range, mainly consisting of mineral material (the Greek litos means stone ). Only bodies created by natural physico chemical… … Wikipedia
Geology of Jersey — The geology of Jersey is characterised by the Late Proterozoic Brioverian volcanics, the Cadomian Orogeny, and only small signs of later deposits from the Cambrian and Quaternary periods. The kind of rocks go from conglomerate to shale, volcanic … Wikipedia
spherulite — GLOSSARY OF VOLCANIC TERMS Typically rounded, radiating arrays of crystal fibers produced by the high temperature devitrification of volcanic glass. In felsic rocks, the crystal fibers are generally composed of alkali feldspar and a silica… … Glossary of volcanic terms
Volcanic rock — is an igneous rock of volcanic origin. Texture Volcanic rocks are usually fine grained or aphanitic to glassy in texture. They often contain clasts of other rocks and phenocrysts. Phenocrysts are crystals that are larger than the matrix and are… … Wikipedia
Variolite — Variolites (Latin varius , speckled, variegated ) are a group of dark green basic igneous rocks that, especially on weathered surfaces, exhibit pale colored spots, or spherules, that give them a pockmarked appearance. In some conditions these… … Wikipedia
Quartz-porphyry — Quartz porphyry, in petrology, is the name given to a group of hemi crystalline acid rocks containing porphyritic crystals of quartz in a fine grained matrix, usually of micro crystalline or felsitic structure. In specimens, the quartz appears as … Wikipedia