Nepheline syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known. Phonolite is the fine-grained extrusive equivalent.
Hand samples of nepheline syenite of the Ordovician Beemerville Complex, northern New Jersey
Nepheline syenite of the Intrusive Complex of Tanguá, State of Rio de Janeiro, Brazil (Motoki et al., 2011a)
Kakortokite (eudialytic nepheline syenite) Kangerdluarssaq Fjord, far-southern Greenland. Slab is 9.5 cm tall.
Pseudoleucite nepheline syenite of the Intrusive Complex of Morro de São João, State of Rio de Janeiro, Brazil (Motoki et al., 2011b)
Nepheline, also called nephelite (from Ancient Greek νεφέλη (nephélē) 'cloud'), is a rock-forming mineral in the feldspathoid group – a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. It is used in glass and ceramic manufacturing and other industries, and has been investigated as an ore of aluminium.
Nepheline
Grayish-white nepheline crystals with dark schorlomite from Bou-Agrao Mount, Tamazeght complex, High Atlas Mountains, Morocco. Size: 6.0 cm × 4.4 cm × 3.8 cm (2.4 in × 1.7 in × 1.5 in)