A Geoscience Digital Image Library

TitleThin seciton of nepheline syenite
DescriptionThis is a photo of a cross polarized thin section of nepheline syenite. Chiefly composed of granular to anhedral aggregates of albite, nepheline and subordinate mafics: biotite and hastingsite. The nepheline is completely anhedral and is readily differentiated from the other felsic species by its lack of twinning, its slightly turbid aspect, its irregular fracture pattern and its alteraion to sericite. The albite is subhedral-tabular. Some sections show slightly curved twin lamellae and minor gradation zoning. The biotite is pleochroic from olive green to very dark green in color and anhedral in form. Accessories can incluse relatively abundant coarse, anhedral, interstitial calcite, which is primary and minor cancrinte, microcline, and sodalite.
Geologic provinceGrenville
LocationCanada ▹ Ontario ▹ Methuen Township. Near Blue Mountain.
PhotographerDarla Sondrol. 2002-04-03.
CollectionWard’s Collection of Classic North American Rocks #17.
Key wordsPrecambrian, nepheline, syenite, Ontario, Canada
Tech details708 KB. Thin section. Nikon FDX-35.
GeoDIL number2561