Quartz as a Devitrification Product of Vitreous Silica*

A bstract Quartz has been observed as a devitrification product of vitreous silica prepared from glass sand when heated for four hours at 1300°C. Another type of commercial vitreous silica did not devitrify under the same conditions. Examination of the various properties of the two samples of vitreous silica by means of the microscope, interferometer, and X‐ray did not disclose differences which would explain the cause of the devitrification. Several theories arc advanced to explain the phenomena observed.