The Quarterly Journal of the Geological Mining and Metallurgical Society of India. September 1953

The second method consists in counting the number of grains under the microscope with the help of mechanical stage and calculating the percentages of the constituent minerals of the black sand from the results thus obtained. [...] From a study of the graph it is seen that the formation of the black sand concetrates depends on the factors such as the proximity to the stream the power of the waves and drift and lastly on the shape and the gradient of the beach. [...] In the area under consideration the occurrence of black sand patches in the beds of the streams cutting through red loamy soil and the occurrence of these deposits at the confluence of the streams prove that these deposits are not dissimilar to the occurrences of the Travancore and are probably of like origin. [...] The occurrence of the mineral in the pegmatites of the area is in confirmation of the observations of the previous workers. [...] The measurements are given in the usual order : (a) Diameter of the shell (b) Height of the outermost whorl (c) Thickness of PI )1 and (d) Width of the umbilicus in min and percentages of the diameter of the shell.