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It's aluminosilicate glass or Al₂SiO₅ with a hardness of about 7 (Mohs scale) at best. Sapphire crystal is Al₂O₃, which has a hardness of 9. So it's hard, but
by gmlk 16y ago
It's aluminosilicate glass or Al₂SiO₅ with a hardness of about 7 (Mohs scale) at best.
Sapphire crystal is Al₂O₃, which has a hardness of 9. So it's hard, but not that hard.