"The present paper deals with the mineralogy of sixty-four samples of bottom deposits from the northern Red Sea collected during the 'Mabahith' Expedition (1934-35). The special character of the wind- borne Red Sea deposits is discussed. The mineralogy of the sediments is uniform over the different provinces and thus contrasts with that of the usual basins of deposition. Local variations are, however, caused by contamination from local source-rocks or variation in the environmental conditions of deposition. The full value of the results can only be estimated when much more work has been done on the contributing rocks of the coastal areas."