More than 150 occurrences or deposits of barite (barium sulphate, BaSO 4) have been recorded in Canada; however, deposits of economic significance are confined largely to Newfoundland, Nova Scotia, Ontario and British Columbia. There are three main producers of barite at present: one with a mine at Brookfield, N.S., another with mines near Matachewan, Ont., and the third with mines near Golden, B.C. Barite occurs in the form of vein, replacement, and residual deposits; vein deposits predominate and form the chief source of commercial barite. Although some deposits are relatively high grade, most ores require beneficiation. Beneficiation commonly includes gravity concentration, e.g., jigging and tabling, magnetic separation and, occasionally, flotation. Barite's high specific gravity (4.5), opaqueness to Xrays, inertness, and whiteness make this mineral suitable for many diverse uses. Barite is used as a weighting agent in drillingmud fluids in oil and gaswell drilling, as a flux in glass and ceramics, and as a filler and extender in paints and plastics. It is also used in pharmaceutical formulations and chemicals manufacture. Barite has been the subject of many laboratory studies by CANMET and other organizations. This report references 51 barite studies by CANMET and eight by others. Summaries of the most important CANMET studies are presented in the Appendix.