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Nepheline syenite is a holocrystalline plutonic rock that consists ... including many informal place-name varieties named after the locations in which they were first ...
Litchfieldite (nepheline syenite gneiss) from Canaã Massif, Brazil. Litchfieldite is a rare igneous rock.It is a coarse-grained, foliated variety of nepheline syenite, [1] sometimes called nepheline syenite gneiss or gneissic nepeheline syenite. [2]
Syenite from Corsica QAPF diagram that shows the quartz (Q), alkali feldspar (A), and plagioclase (P) composition of syenite Leucocratic variety of nepheline syenite from Sweden Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite , but deficient in quartz , which, if present at all, occurs in ...
[1] [2] The complex is chiefly made up of peralkaline nepheline syenite and is rich in exotic minerals. [1] Rocks of the complex intruded into the Paleoproterozoic-aged Växjo granites of the Transscandinavian Igneous Belt. [1] [2] Alfred Elis Törnebohm was the first to describe the rocks of Norra Kärr in 1906.
Lujavrite, a dark agpaitic nepheline syenite, occurs as an internal layer in the north Ilimaussaq complex. The uppermost sections generally have the highest rare-earth elements, uranium and zinc grades. Lujavrite is a rare variety of nepheline syenite having amphibole, aegirine pyroxene, nepheline and feldspar.
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For example, a syenite with significant nepheline present can be termed a nepheline-bearing syenite or nepheline syenite, with the term nepheline replaceable by any foid mineral. Such terminology is used in the Streckeisen classification of igneous rocks. [2]
Nepheline, also called nephelite (from Ancient Greek νεφέλη (nephélē) 'cloud'), is a rock-forming mineral in the feldspathoid group – a silica-undersaturated aluminosilicate, Na 3 K Al 4 Si 4 O 16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites.