History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c12.s1.t4.30

v1.c12.s1.t4.30

The process of the extraction of the gold after the quartz had reached the surface are quite clear. The quartz was broken to about the size of a walnut in small cup shaped depressions in an adjacent dyke and was then introduced beneath great granite boulders which were rocked to and fro, crushing the quartz to powder by their own weight. The bottom rock on which crushing took place was preferably a diabase dyke, but where these were not available as at Wandalli, the harder Schist bands were used. The upper crushing stones were of intrusive diabase or of granite. Probably the boulders were transported to Wandalli from Yelagatti where they were formed by nature from porphyritic granite. Some of those boulders weighed more than 18 cwts. Crushing stones are occasionally found at considerable distances from quartz veins, and it would seem that it was only during the rains that crushing was effected near the workings where these were located at some distance from a water course.