Leucite — is a rock forming mineral composed of potassium and aluminium tectosilicate K [AlSi2O6] . Crystals have the form of cubic icositetrahedra but, as first observed by Sir David Brewster in 1821, they are not optically isotropic, and are therefore… … Wikipedia
Syenite — Sy e*nite, n. [L. Syenites (sc. lapis), from Syene, Gr. ?.] (Min.) (a) Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called {granite}. (b) A granular, crystalline, ingeous rock… … The Collaborative International Dictionary of English
Syenite — is a coarse grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts ( … Wikipedia
nephelite elaeolite syenite — Syenite Sy e*nite, n. [L. Syenites (sc. lapis), from Syene, Gr. ?.] (Min.) (a) Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called {granite}. (b) A granular, crystalline, ingeous … The Collaborative International Dictionary of English
syenite — syenitic /suy euh nit ik/, adj. /suy euh nuyt /, n. a granular igneous rock consisting chiefly of orthoclase and oligoclase with hornblende, biotite, or augite. [1790 1800; < L syenites (lapis) (stone) of SYENE < Gk syenítes (líthos); see ITE1] * … Universalium
Nepheline syenite — of the Intrusive Complex of Tanguá, State of Rio de Janeiro, Brasil (Motoki et al., 2011a) Nephelene syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or… … Wikipedia
granite — Syenite Sy e*nite, n. [L. Syenites (sc. lapis), from Syene, Gr. ?.] (Min.) (a) Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called {granite}. (b) A granular, crystalline, ingeous … The Collaborative International Dictionary of English
Geochemistry — The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks and soils, and the cycles of matter and energy that transport the Earth s… … Wikipedia
Borolanite — is one of the most remarkable rocks of the British Isles, found on the shores of Loch Borolan in Sutherland shire, after which it has been named. In this locality there is a considerable area of granite rich in red alkali feldspar, and passing,… … Wikipedia
Feldspathoid — The feldspathoids are a group of tectosilicate minerals which resemble feldspars but have a different structure and much lower silica content. They occur in rare and unusual types of igneous rocks.Foid, contraction of the term feldspathoid, is… … Wikipedia
