The Campbell-Caldwell iron deposit is a lens of fine- to coarse-grained magnetite within an aluminous metasediments unit of the Grenville Supergroup. It is approximately 3,250 feet long, 69 to 324 feet wide and extends to a depth of 1,650 feet. The average iron content is 22.3%. Magnetite, hornblende, clinopyroxene, biotite, calcite, scapolite, tourmaline, quartz, epidote group minerals,- apatite, secondary chlorite, secondary , hematite, pyrite, pyrrhotite and chalcopyrite compose the deposit. The rocks of the area include amphibolite, aluminous metasediments and marble of the Grenville Supergroup that have been intruded by gabbro and syenite and except for the syenite all have been metamorphosed to amphibolite grade. Two other iron deposits, Bluff Point and Martel, occur within the study area and are geologically similar to the Campbell-Caldwell deposit. A literature compilation of all known iron deposits within southeastern Ontario and southwestern Quebec of the Central Metasedimentary Belt was undertaken and a classification for these deposits was proposed. A sedimentary origin is favored for the genesis of the Campbell-Caldwell, Bluff Point and Martel iron deposits. All features of these deposits are compatible with this theory.