Syenite

leucocratic variety of nepheline syenite from Sweden (särnaite).

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 (<5%). Image File history File links Syenite. ... Image File history File links Syenite. ... Image File history File links Nepheline-syenite-2005. ... Image File history File links Nepheline-syenite-2005. ... Nephelite, also called nepheline, is a feldspathoid -- a silica-undersaturated aluminosilicate, Na,K) AlSiO4, that occurs in intrusive and volcanic rocks undersaturated with silica, and in their pegmatites. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when rock (magma) cools and solidifies, with or without crystallisation, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Quarrying granite for the Mormon Temple, Utah Territory. ... Quartz is one of the most common minerals in the Earths continental crust. ...

The feldspar component of syenite is predominantly alkaline in character (usually orthoclase) . Plagioclase feldspars may be present in small quantities, less than 10%. Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ... The common (Arrhenius) definition of a base is a chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. ... Orthoclase (KAlSi3O8) is an important tectosilicate mineral, which forms igneous rock. ... Lunar Ferroan Anorthosite #60025 (Plagioclase Feldspar). ...

When present, ferromagnesian minerals are usually hornblende amphibole, rarely pyroxene or biotite. Biotite is rare, because in a syenite magma most aluminium is used in producing feldspar. Amphibole (Hornblende) Hornblende is a complex inosilicate series of minerals. ... For the logical fallacy, see Amphibology. ... Figure 1:Mantle-peridotite xenolith with green peridot olivine and black pyroxene crystals from San Carlos Indian Reservation, Gila Co. ... A Biotite slice Biotite is a common phyllosilicate mineral that contains potassium, magnesium, iron and aluminium. ...

Syenites are usually peralkaline and peraluminous, with high proportions of alakali elements and aluminium. Peraluminous rocks are igneous rocks that have a molecular proportion of aluminum oxide greater than that of sodium oxide and potassium oxide combined. ...

Syenites are formed from alkaline igneous activity, generally formed in thick continental crustal areas, or in Cordilleran subduction zones. To produce a syenite, it is necessary to melt a granitic or igneous protolith to a fairly low degree of partial melting. This is required because potassium is an incompatible element and tends to enter a melt first, whereas higher degrees of partial melting will liberate more calcium and sodium, which produce plagioclase, and hence a granite, adamellite or tonalite. The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. ... Protolith refers to the precursor rock of a given lithology. ... Quarrying granite for the Mormon Temple, Utah Territory. ... Tonalite is an igneous, plutonic (intrusive) rock, of felsic composition, with phaneritic texture. ...

At very low degrees of partial melting a silica undersaturated melt is produced, forming a nepheline syenite, where orthoclase is replaced by a feldspathoid such as leucite, nepheline or analcime. Nephelene syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. ... The feldspathoids are a group of tectosilicate minerals which resemble feldspars but have a different structure and much lower silica content. ... Leucite or amphigene is a rock-forming mineral composed of potassium and aluminium metasilicate KAl(SiO3)2. ... Nephelite, also called nepheline, is a feldspathoid -- a silica-undersaturated aluminosilicate, Na,K) AlSiO4, that occurs in intrusive and volcanic rocks undersaturated with silica, and in their pegmatites. ... Analcite or analcime (from the Greek analkimos - weak) is a white, grey, or colourless tectosilicate mineral. ...

Syenite is not a common rock, some of the more important occurrences being in New England, Arkansas, Montana, New York (syenite gneisses), Switzerland, Germany, and Norway. This article is about the region in the United States of America. ... Official language(s) English Capital Little Rock Largest city Little Rock Area  Ranked 29th  - Total 53,179 sq mi (137,732 km²)  - Width 239 miles (385 km)  - Length 261 miles (420 km)  - % water 2. ... Official language(s) English Capital Helena Largest city Billings Area  Ranked 4th  - Total 147,165 sq mi (381,156 km²)  - Width 255 miles (410 km)  - Length 630 miles (1,015 km)  - % water 1  - Latitude 44°26N to 49°N  - Longitude 104°2W to 116°2W Population  Ranked... NY redirects here. ... Gneiss Gneiss (IPA: ) is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. ...

Etymology

The term syenite was originally applied to hornblende granite like that of Syene in Egypt, from which the name is derived. Syene was the ancient Greek name for the Southern Egyptian town of Aswan. ...

Episyenite

Episyenite (or epi-syenite) is a term used in petrology to describe to the result of alteration of a [[SiO₂]] rich rock to a more SiO₂ depleted rock. The term stems from "epi" and syenite. Petrology is a field of geology which focuses on the study of rocks and the conditions by which they form. ...

The process which results in SiO₂ depletion can be termed episyenitization. This process is only referring to the macroscopic result of relative SiO2 depletion in a rock. The actual physical process leading to this SiO₂ depletion may vary in a given metamorphic environment. Diffusion of chemical components in a stagnant fluid, related to differences in chemical potential or pressure as well as advection of a SiO₂- undersaturated fluid may lead to the dissolution of quartz from the un-altered rock, thus depleting it of this component. Macroscopic is commonly used to describe physical objects that are measurable and observable by the naked eye. ... The term Metamorphic can be associated with a number of meanings:- Metamorphic rock The term for rocks that have been transformed by extreme heat and pressure. ... Advection is the transport of a conserved scalar quantity that is transported in a vector field. ... Quartz is one of the most common minerals in the Earths continental crust. ...

See also:

• list of minerals
• list of rocks

Luke i like nachos!!!! Nachos!!! Fat Gem animals. ... This page is intended as a list of all rock types. ...