This document summarizes a lecture on abrasives. It defines abrasives as hard minerals used for grinding and polishing other materials. It outlines the objectives of describing the types of abrasives, their compositions, common uses, and important properties. The types are natural like diamond, corundum, and emery or synthetic like silicon carbide. Their main uses include grinding, polishing, buffing, drilling, cutting, and sanding. Key properties are hardness, toughness, and resistance to attrition.