Product and process for forming same

摘要

Colored and/or transparent, low-expansion, crystallized glass-ceramics formed by thermal in situ crystallization from a differently colored crystallizable base glass and having lithium-containing crystals as the predominant crystalline species. The products have coefficients of thermal expansion of less than about 12 x 10-7 per DEG C. over the range of 0 to 300 DEG C. Telescope mirror blanks can be made from the transparent, low-expansion, crystallized glass-ceramics.