Pure transparent quartz glass and process for production thereof

摘要

Pure transparent quartz glass is provided by molding powdery amorphous silica into an article, converting the molded powdery amorphous silica into crystalline silica of high-temperature type cristobalite structure, and then fusing the crystalline silica, the quartz glass containing impurities respectively at a content of no higher than 1 ppm, and OH groups at a content of no higher than 20 ppm, and having a viscosity of 10<12.0> poise or more at 1200 DEG C. The quartz glass is transparent and has high purity, and is excellent in high temperature viscosity characteristics. The quartz glass can be produced at low cost.