Abstract Mississippi Valley-type (MVT) lead-zinc deposits typically are composed of galena and sphalerite occurring as openspace fillings in carbonate breccias; replacement of host rocks is relatively minor except in high grade zones. The deposits owe their commonly accepted name to the fact that several classical districts occur within the drainage basin of the Mississippi River, central U.S.A. Important Canadian examples include Pine Point, Polaris, Nanisivik, Newfoundland Zinc, and Monarch-Kicking Horse deposits; of lesser importance are the deposits at Gays River, Nova Scotia and Robb Lake, British Columbia (Fig. 10-1).