Nepheline
Mineral (Na,K)AlSiO4
Also called Elaeolite
About it
Greasy grey grains in silica-poor rocks that never contain quartz; weathered surfaces become pitted. Bancroft, Ontario, and the Kola Peninsula, Russia, are well known.
- Type
- Mineral
- Group
- Silicate (tectosilicate), nepheline group
- Formula
- (Na,K)AlSiO4
- Hardness (Mohs)
- 5.5–6
- Specific gravity
- 2.55–2.67
- Streak
- white
- Lustre
- vitreous (glassy), greasy
- Crystal system
- Hexagonal
- Colours
- white, grey, yellowish, brown, greenish, reddish
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- indistinct; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.