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Kathy Feick
Nepheline is an important feldspathoid mineral. It is white, grey or yellow in colour with a vitreous lustre and a poor cleavage. The name Nepheline comes from the Greek word nephele, which means “cloud,” because it becomes strongly clouded when put in strong acid.
Nepheline only forms in silica-poor rocks. It is almost never associated with quartz. It may be found in some contact metamorphosed rocks otherwise it occurs in alkaline complexes in igneous rocks. Nepheline is mostly found in the rock Nepheline Syenite in nature.
Uses:
- Glass (used as a flux to lower the melting temperature, gives increased resistance to scratching and breaking, improved thermal endurance, increased chemical curability).
- Ceramics (used as a flux to lower the melting temperature)
- Roofing Granules
- Rock wool insulation
- Building Stone
- To make Toilet bowls and sinks
Nepheline. Lot 14, Con IV, Monmouth Twp. University of Waterloo Earth Sciences Museum Collection.
Occurrences:
Feldspathoid minerals are rare in nature. That being said, the most common feldspathoid is Nepheline. Although there are a number of localities where Nepheline may be found most occurrences do not yield high amounts of the mineral.
- One occurrence in Great Britain
- One occurrence in France
- One occurrence in Portugal
- Bohemia
- Norway
- Sweden
- Finland
- U.S.
- Canada
- Brazil
- South Africa
- Madagascar
- India
- Tasmania
- Timor
- Turkestan
Nepheline in Canada:
There is a large deposit of Nepheline Syenite in Canada close to Havelock, Ontario. This deposit encompasses 3,500 acres of land and is actively mined by the company Unimin Canada Limited. This company is Canada sole Nepheline provider. It has two operating plants at its Blue Mountain deposit (the Havelock deposit), which is located about 175 kilometres northeast of Toronto, Ontario. Production of marketable Nepheline Syenite was estimated to be about 710,000 tons in 2004. The major use of the Nepheline taken from this quarry is for ceramics such as toilet bowls and sinks. Unimin is a very environmentally conscious company. A number of steps have been taken to reclaim the land that is used.
Nepheline. Davis Hill near Bancroft, Ontario. University of Waterloo Earth Sciences Museum Collection.The world's largest crystals of nepheline are found at this locality. Crystals measuring up to 60 cm have been reported from this deposit. The crystals occur in calcite veins associated with a metamorphic rock called nepheline gneiss. Other minerals associated with nepheline include biotite mica (black), antiperthite feldspar (grey) and sodalite (blue). The deposit was opened as a mica prospect in the early 1900s. This specimen was collected by the National Museum of Canada about fifteen years ago.
References:
Nepheline-the silicate minerals