GRAVIMETER PROSPECTING FOR CHROMITE IN CUBA

Abstract

As a contribution to the War Production Board’s program of exploration for strategic minerals and under an arrangement with the Bethlehem Steel Company, Gulf Research & Development Company, in early 1942, made gravimeter surveys in the chromite bearing Camaguey District, Cuba. One large chromite deposit, under and between two adjacent gravity anomalies, which has been outlined to date by core drilling based on the results of this work, constitutes a substantial addition to the chrome ore reserves of the district. Chrome ore bodies occur in or are associated with igneous rocks. Extensive density determinations of selected rock samples revealed that the chrome ore has a positive density contrast of about 1.5 with respect to the serpentine rock in which it occurs, but also that local occurrences of various other types of igneous rocks, as well as weathered surface material, cause appreciable density contrasts. The technical aspects of the gravimeter field work are discussed. Many gravity anomalies were found; subsequent geological field work and a systematic program of test drilling proves the anomalies to arise from a variety of causes. Typical examples of gravity anomalies due to chromite deposits and to various igneous rock masses are presented. The paper concludes with brief comments on the economic significance of the work.