Dry polishing of opaque minerals

The process of polishing opaque minerals is restudied with the hope of speeding up the process without undue loss of quality. It is found that the physical character and structure of a lap have a marked effect, both in grinding and polishing. The composition and structure of laps found satisfactory are presented. Determinations are given of the rate of removal of material during the various stages of grinding and polishing. Various types of mechanical heads are described, the method of charging laps is discussed in detail, and the complete process of mounting and polishing is outlined, together with illustrations of the various types of polish.