Nepheline
Image: <a rel="nofollow" class="external text" href="https://www.mindat.org/user-24541.html">Douglas Watts</a> (CC BY 3.0)
Mineral NameNepheline
Chemical Formula(Na,K)AlSiO4
Mohs Hardness5.5
Crystal Systemhexagonal
Lustervitreous
Streak Colorwhite
Cleavagepoor on {1010} and {0001}
Fractureconchoidal
Specific Gravity2.6
Colorswhite, grey, greenish-grey
Transparencytranslucent
Type LocalityDennis Hill locality (Litchfield sodalite locality), Litchfield, Kennebec County, Maine, USA
Mineral GroupSilicates
Usesindustrial, collector
Associated Mineralsalbite, cancrinite
Rarityuncommon
Description
This image displays a polished chunk of nepheline, showing a predominantly light grey to whitish color with areas of greenish-grey banding and scattered dark inclusions. The surface exhibits a somewhat granular and crystalline texture.
Geological Context
Nepheline is a feldspathoid mineral typically found in silica-undersaturated igneous rocks such as nepheline syenites, phonolites, and some alkaline volcanic rocks. It forms in environments where there is insufficient silica to form feldspar.
