nephelinite

nephelinite
—nephelinitic /nef'euh leuh nit"ik/, adj.
/nef"euh leuh nuyt'/, n. Petrog.
a fine-grained, dark rock of volcanic origin, essentially a basalt containing nepheline but no feldspar and little or no olivine.
[1860-65; NEPHELINE + -ITE1]

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▪ lava
      silica-poor (mafic) lava that contains nepheline and pyroxene and is usually completely crystallized. Despite its wide geographic distribution and occasional extensive local development, it is a very rare rock. Known only from Tertiary strata (about 2,500,000 to 65,000,000 years in age), nephelinites are abundant in the Canary Islands, the Azores, the Cape Verde Islands, and Isla Fernando de Noronha off the coast of Brazil. The pyroxene in nephelinites may be either titanium-rich augite or aegirine; plagioclase, if present, is commonly labradorite. Varieties rich in leucite and haüynite are well known. Biotite is characteristic in some types; amphibole is scarce. Accessory minerals may include sanidine, melilite, sodalite, perovskite, apatite, and chromite.

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Universalium. 2010.

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  • Nephelinite — lava (grey) containing a xenolith of peridotite (yellow), Kaiserstuhl, Germany. Nephelinite is a fine grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite). If olivine is present, the rock may… …   Wikipedia

  • néphélinite — ● néphélinite nom féminin Lave riche en néphéline …   Encyclopédie Universelle

  • nephelinite — [nef′ə lin īt΄] n. [< NEPHELINE + ITE1] a grayish, fine grained or porphyritic igneous rock composed mainly of nepheline and pyroxene …   English World dictionary

  • nephelinite — noun Etymology: International Scientific Vocabulary Date: circa 1863 a silica deficient igneous rock having nepheline as the predominant mineral • nephelinitic adjective …   New Collegiate Dictionary

  • nephelinite — noun a dark, finely crystalline rock of volcanic origin, being a mixture of nepheline and pyroxene …   Wiktionary

  • nephelinite — neph·e·lin·ite …   English syllables

  • nephelinite — neph•e•lin•ite [[t]ˈnɛf ə ləˌnaɪt[/t]] n. a fine grained, dark rock of volcanic origin, essentially a basalt containing nepheline but no feldspar and little or no olivine • Etymology: 1860–65 neph e•li•nit′ic ˈnɪt ɪk adj …   From formal English to slang

  • nephelinite — /ˈnɛfələnaɪt/ (say nefuhluhnuyt) noun a fine grained, dark rock of volcanic origin, essentially a basalt containing nepheline but no felspar and little or no olivine. {nephelin(e) + ite1} …  

  • nephelinite — noun an igneous rock consisting of nepheline and pyroxene • Hypernyms: ↑mineral • Substance Meronyms: ↑nepheline, ↑nephelite, ↑pyroxene …   Useful english dictionary

  • Geology of Tasmania — Tasmania has a varied geological history, with the world s biggest exposure of diabase, or dolerite. Rocks from the Neoproterozoic, Paleozoic and Mesozoic time periods appear. It is one of the few southern hemisphere areas glaciated during the… …   Wikipedia

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