PURPOSE: To use canasite glass-ceramics for building materials having strong and bright colors while keeping soft opaqueness.

CONSTITUTION: These glass-ceramics are composed of, by weight in terms of oxide of about 45 to 75% SiO2, about 8 to 30% CaO, about 3.5 to 12% F, about 3 to 15% Na2O, about 0 to 20% K2O, about 5 to 25% Na2O+K2O, about 0 to 6% B2O3, about 0 to 7% Al2O3, about 0 to 12% ZrO2 and about 0.02 to 1.5% total of at least one component selected from the group consisting of Cr2O3 and Co3O4.