OPAQUE QUARTZ GLASS AND PRODUCTION METHOD THEREOF

[Problem] To provide an opaque quartz glass having excellent heat shielding properties, mechanical strength, and surface smoothness. [Solution] An opaque quartz glass having excellent heat shielding properties, mechanical strength, and surface smoothness, wherein silicon nitride beads having an average size of 0.1-0.3 mm are used as a grinding medium in wet grinding of a slurry containing 45-75 wt% of silica powder dispersed in water so that the silicon nitride generated as a result of wearing of the silicon nitride beads functions as a foaming agent, whereby the opaque quartz glass includes independent spherical air bubbles having an average size of 2-30 mu m, has a density of 1.90-2.20 g/cm and a whiteness of 80 or more, and/or, when having a thickness of 3 mm, has a reflectance of light having a wavelength of 0.2-3 mu m of 80% or more, a bending strength of 70 MPa or more, and a surface roughness Ra for a baking-finished surface of 0.7 mu m or less. 【课题】本发明提供一种热线屏蔽性、机械强度、表面平滑性优异的不透明石英玻璃。【解决手段】本发明通过对将二氧化硅粉末