nepheline-syenite
nepheline-syenite A medium- to coarse-grained igneous rock consisting of essential alkali feldspar (see ESSENTIAL MINERAL), nepheline, pyroxene (aegirine-augite or sodic hedenbergite) and amphibole (ferrohastingsite, NaCa2(Fe2+)4AlAl2Di6O22(OH)2, which is essentially a sodic, iron-rich hornblende, barkevikite and/or arfvedsonite) with accessory sphene, apatite, titanomagnetite, ilmenite, and zircon (see ACCESSORY MINERAL). The rock is, in effect, a syenite which is undersaturated in silica (see SILICA SATURATION).
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Norite , norite A coarse-grained, basic igneous rock consisting of essential plagioclase feldspar, orthopyroxene (hypersthene or bronzite), and clinopyroxene… essential , es·sen·tial / iˈsenshəl/ • adj. 1. absolutely necessary; extremely important: it is essential to keep up-to-date records. ∎ fundamental or central to… Peridotite , peridotite A coarse-grained, ultrabasic, igneous rock consisting of essential magnesium-rich olivine accompanied by lesser amounts of other ferromagn… Arenaceous , arenaceous Sandy, or sand-like in appearance or texture. The term is applied to clastic sedimentary rocks with a grain size of 0.0625–2.00 mm. Three… Iron Ores , Rocks
Rocks are composed of minerals, which are natural inorganic (nonliving) substances with specific chemical compositions and structures. A rock m… Basic Rock , basic rock Rock with a relatively high concentration of iron, magnesium, and calcium, and with 45–53% of silica by weight. Examples include gabbro, w…
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nepheline-syenite