rare, dark-coloured, intrusive igneous rock that contains augite and orthoclase feldspar as its primary constituents. Other minerals include olivine, biotite, and nepheline, with little plagioclase feldspar and no quartz. At Shonkin-Sag, in the Highwood Mountains, Montana, shonkinite forms the greater part of a stratified laccolith (inserted between sedimentary beds). It also occurs in Ontario, British Columbia, and Indonesia (Celebes, Timor).

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  • shonkinite — shon·kin·ite …   English syllables

  • shonkinite — ˈshäŋkəˌnīt noun ( s) Etymology: Shonkin (Highwood mountains, Montana), its locality + English ite : a dark granular igneous rock consisting of augite with subordinate orthoclase and smaller amounts of olivine, biotite, nephelite, sodalite, and …   Useful english dictionary

  • Theralite — (from Greek to pursue ) is, in petrology, a group of plutonic holocrystalline rocks consisting of nepheline, basic plagioclase, augite and olivine, and so called because of its rare occurrence. Its discovery was looked forward to with interest as …   Wikipedia

  • Carbonatite — Carbonatites (pronEng|kɑrˈbɒnətaɪt) are intrusive or extrusive igneous rocks defined by mineralogy that comprises more than 50 volume % carbonate minerals. Carbonatites may be confused with marble, and may require geochemical… …   Wikipedia

  • monzonite — monzonitic /mon zeuh nit ik/, adj. /mon zeuh nuyt /, n. any of a group of granular igneous rocks having approximately equal amounts of orthoclase and plagioclase feldspar, intermediate in composition between syenite and diorite. [1880 85; < G… …   Universalium

  • theralite — /thear euh luyt /, n. a coarse grained, phaneritic rock composed of labradorite, nepheline, and augite. [ < Gk théra hunting + LITE; said to be so called because success in hunting it down was thought to be certain] * * * ▪ mineral       any… …   Universalium

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