Fig. 9From: Opaque ancient K2O–PbO–SiO2 glass of the Southern Song Dynasty with fluorite dendrites and its fabricationa The appearances of the quartz glass boats before and after firing process; b the microstructure of the amorphous silica surface layer, showing a new reaction layer formed on the amorphous silica with volatile K2O and PbO; and c the transparent layer free of fluorite dendrites near the surface of the Replica 2Back to article page