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This is an accepted version of this page This is the latest accepted revision, reviewed on 29 January 2025. Classified advertisements website Craigslist Inc. Logo used since 1995 Screenshot of the main page on January 26, 2008 Type of business Private Type of site Classifieds, forums Available in English, French, German, Dutch, Spanish, Italian, Portuguese Founded 1995 ; 30 years ago (1995 ...
Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. [13] Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations, spherulitic, nodular, and lithophysal structures. Some rhyolite is highly vesicular pumice. [5]
"Imperial Porphyry" from the Red Sea Mountains of Egypt A waterworn cobble of porphyry Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in). Porphyry (/ ˈ p ɔːr f ə r i / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.
It is also found in the Czech Republic and the Mediterranean area near Italy. For localities in the United States, phonolite can be found in the Black Hills Forest in South Dakokta. The most well known phonolite-composed natural structure is the Devil's Tower , found in Wyoming.
Quartz porphyry from the island of Alnö, Sweden. Phenocrysts of clear glassy rounded quartz and white orthoclase feldspar are set in a fine-grained matrix. Sample is just over 10 cm long. Quartz-porphyry, in layman's terms, is a type of volcanic rock containing large porphyritic crystals of quartz.
Porphyry (geology), an igneous rock with large crystals in a fine-grained matrix, often purple, and prestigious Roman sculpture material; Shoksha porphyry, quartzite of purple color resembling true porphyry mined near the village of Shoksha, Karelia, Russia; Porphyritic, the general igneous texture of a rock with two distinct crystal ...
glassybaby is a company based in Seattle, Washington that produces handmade glass votive candle holders, called glassybaby, which are sold online and at stores in the Seattle area and Oregon. The company plans to open a store in Montana as of 2023 [update] .
In extrusive rocks, the phenocrysts are surrounded by a fine-grained (aphanitic) matrix or groundmass of volcanic glass or non-visible crystals, commonly seen in porphyritic basalt. Porphyritic intrusive rocks have a matrix with individual crystals easily distinguished with the eye, but one group of crystals appearing clearly much bigger than ...