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.