The intrusion does not outcrop, but boulders of carbonatite and alkaline rocks have been found on the shore of Carb Lake. A strong, approximately circular magnetic anomaly has a diameter of about 3 km (Ferguson, 1971, Map). Drilling has indicated that the central area is underlain principally by carbonatite of about equal proportions of calcite and dolomite, with about 20% apatite, magnetite, biotite, pyrochlore and melanocratic rock fragments. Bands of the latter rock type, which appear to be vertical, consist of 30-60% magnetite, with apatite, a sodic amphibole, biotite, pyrite and pyrochlore. Fluorite, vermiculite, synchisite and ancylite have been identified.
FERGUSON, S.A. 1971. Columbium (niobium) deposits of Ontario. Mineral Resources Circular, Ontario Department of Mines and Northern Affairs, 14: 1-58.