This document discusses various classifications of ore deposits that have been proposed over time. It describes six major classifications: Niggli (1929), Schneiderhöhn (1941), Lindgren (1913, revised 1933, modified 1968), Bateman (1942, revised 1950, revised 1979), Stanton (1972), and Guilbert and Park (1986). The classifications vary in their criteria but most are based on the nature of the ore-bearing fluid, origin, environment of formation, or process of deposition. The purpose is to group deposits with similar characteristics to better understand their genesis and aid in exploration. No single classification is perfect as deposits can have complex origins and classifications are subject to revision.