Patent ID: 8257831

Claim:
Glass-ceramics comprising SiO 2 , Al 2 O 3 and Li 2 O on oxide basis, wherein the glass-ceramics contains in mass % SiO 2 40-60%, MgO 0-9%, TiO 2 0-4.5%, and one or both of K 2 O 1-7% and Na 2 O 1-7%, wherein total amount in mass % of SiO 2 and Al 2 O 3 is less than 77%, and Li 2 O/(SiO 2 +Al 2 O 3 ) which is the ratio in mass % of the amount of Li 2 O to the total amount of SiO 2 and Al 2 O 3 being 0.064 or over, and the glass-ceramics comprises at least one crystal phase selected from the group consisting of β-quartz, β-quartz solid solution, β-eucryptite, β-eucryptite solid solution, β-spodumene and β-spodumene solid solution.