epheline syenite is a white to whitish-grey, medium• grained igneous rock resembling granite in texture. It consists of nepheline, potash and soda feldspar. and accessory mafic minerals such as biotite, hornblende and magnetite. Although nepheline syenite is a rock type known to occur in many parts of Canada, its industrial application is limited to those deposits in which iron-bearing accessory minerals can readily be removed; its major uses are in the glass and ceramics industries. •
Nepheline syenite as a raw material for glass, ceramic and filler industries was first developed in Canada, which was the world's sole producer for many years. Canada's only competitor in the field, Norway, began nepheline syenite mining and milling in 1961. Although the U.S.S.R. began mining nepheline syenite on the Kola Peninsula during the 1930s, the deposit was worked for its phosphate content. Byproduct nepheline from the Kola deposit became important as a source of aluminum and is still being used for this purpose. Nepheline syenite is also quarried in the United States for use as aggregate, railway ballast, ieuystone and roofing granules.
Canada's nepheline syeniie industry began in 1932 with the stakingof five claims on Blue Mountain, 25 miles northeast of Peterborough. A long period of persistent efforts in technical aml market research anJ development was necessary befcre this unique industry became established. Today there are two mills in operation on Blue Mountain •_processing rock from several quarries.
Over the years nepheline syenite has become preferred to feldspar as a source of essential alumina
and the alkalis in glass manufacture. Its use has resulted in more rapid melting of the batch at lower temperatures than with feldspar, consequently reduc•
ing fuel consumption, lengthening the life of furnace refractories and improving the yield and quality.
Industrial uses for nepheline syenite other than for glass manufacture are many; and markets are expand• ing rapidly in ceramics, enamels, and as a filler in• paints, papers. plastics anJ foam rubber.
Feldspar is the name of a group ol minerals consisting of aluminum silicates of potassium, sodium and calcium. Feldspar is used in 1:lassmaking as a source of alumina and the alkalis, ceramic bodies and
glazes, in cleaning compounds as a moderate abrasive and as a flux coating on welding rods. High-calcium feldspars, such as labradorite, and feldspar-rich rocks such as anorthosite find limited use as building stones and for otherdecorative purposes. Dental spar, which is used in the manufacture of artificial teeth, is a pure white potash feldspar free of iron and mica. Feldspar occurs in many rock types, but commer•cially viable deposits are mostly restricted to coarse•grained granite pegmatites from which the mineral is concentrated by flotation or less commonly, hand•cobbing. It is then ground to the desired size. Nearly all feldspar which has been produced in Canada has come from pegmatites in the Precambrian rocks of southern Ontario and southwestern Quebec.

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