Circular describing industrial mineral deposits, excluding aggregates, of northern Ontario (north and west of the Grenville Front). Information was compiled in 1979-81 through literature search of publications and files int he Toronto offices of the Ontario Geological Survey and the Offices of Regional and Resident Geologists. Deposit descriptions are listed by National Topographic System location, in numerical order, then compass order (northwest, northeast, southwest, southeast), then alphabetical order by commodity and deposit name. The name assigned to the deposit is that by which the deposit is commonly known or it is a reference to the company which holds the claim or did work on the deposit. For each deposit, location is given, by the NTS number and by latitude and longitude. Descriptive remarks are also given.