abstract:Cer-Vit aka CerVit or Cervit or Cer-Vit C-101 (from 'ceramic-vitreous'), is a glass-ceramic material made up of oxides of silicon, aluminium and lithium, with ultra low coefficient of thermal expansion, used for telescope mirrors and lenses. It was made by Owens-Illinois Owens Corning in 1967, and discontinued in 1978.