36 CRYOLITE. Cryolite consists of a double fluoride of aluminium and sodium, represented by the formula NaaAl F 6 . It occurs as a secondary mineral in veins. The main source of supply is Greenland. It has not been found in commercial quantities in Canada. Cryolite finds its principal use, in Canada, in the electrolytic reduction of aluminium, in which process it acts as an electrolyte. It is used to a small extent in the manufacturing of opal glass. Amount of cryolite used in the manufacturing industries, as reported by the consumers:— Location No. of firms reporting consumption Domestic Imported Tons Tons 1 242 Ontario 1 m Prairie Provinces Canada (Total) 2 — 24348 The following imports are reported by the Department of Customs:— 1910-1911 1911-1912 1912-1913 cwt. $ cwt. $ cwt. $ 9,618 48,244 7,996 35,639 13,751 57,780 Cryolite