PROBLEM TO BE SOLVED: To provide a glass block excellent in the property of being ground.SOLUTION: The glass block comprises a glass ceramic of a semi-crystalline state and is constituted so that the glass block contains 30,000 pieces/mmor more pores each having 0.1-0.5 μm diameter on the inside thereof. Since the glass block has such a constitution, glass is exfoliated by using the pore as a starting point when grinding work is performed on the glass block. As a result, the property of being ground can be made excellent and a load imposed on a grinding unit can be made smaller. Accordingly, the grinding work can be performed efficiently in a short time and abrasion of a grinding tool can be reduced.SELECTED DRAWING: Figure 1
