Alkaline Rocks and Carbonatites of the World

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Calvin Township

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Occurrence number: 
031-00-089
Country: 
Canada
Region: 
Ontario
Location: 
Longitude: -78.9, Latitude: 46.28

A small area (1.3 km2) of nepheline syenite gneiss occurs 19 km southwest of the town of Mattawa. The gneiss contains 5-25% nepheline, sodic hastingsite, 40-60% oligoclase and sometimes garnet. A pyroxene, which is present in some rocks, is described as omphacite.

References: 
LUMBERS, S.B. 1976. Omphacite-bearing nepheline syenite in an anorthosite complex, Grenville Province of Ontario. (Abstract). Geological Association of Canada - Mineralogical Association of Canada, Annual Meeting, Edmonton, Program with Abstracts, 1: 73
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