THE EFFECT OF TEMPERATURE ON THE STRUCTURE OF SOAPSTONE*

A rstract Samples of soapstone from a deposit in the Cascade Mountains of Washington were heated to various temperatures, draw trials were made, and the effect of temperature on the structure and texture was studied microscopically. The results obtained indicate a change of the talc to enstatite at about 1000°C. with a further change to clinoenstatite at about 1200°C. At the higher temperatures iron impurities have united with silica, probably to form fayalitc along the original impure schistosic planes of the soapstone.