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The Great Bear magmatic zone, Northwest Territories, hosts numerous giant quartz veins and stockwork zones. These zones can be up to 100m wide and up to 10km long, with two or more generations of quartz. A few of the giant quartz vein zones host base-metal uranium mineralization, and some are proximal to mineralization, although most are barren. Cathodoluminescence imaging shows the quartz veins have complex growth zones and a trace element study suggests that these zones are the result of Al and Li substitution in the quartz lattice. Oxygen isotope (18Oqtz) values of quartz generally fall between +8 to +14.6 (VSMOW). Fluid inclusion homogenization temperatures range from 100 to 375C, and the fluids have variable salinities. The fluids that created the giant quartz veins are epithermal in nature with a meteoric water brine signature, and formed as a result of multiple fluid pulses and re-fracturing events.