Figure 4

Chemical composition of ceramic matrix (grains < 50 µm) normalized to 100 wt.%: (a) SiO₂-Al₂O₃-CaO: a1) Ransyrt 1; a2) Kabardinka 2; a3) Levinsadovka-Saf’janovo; (b) at-f-alc (at = CaO + MgO; f = Fe₂O₃; alc = K₂O + Na₂O): (b1) Ransyrt 1; (b2) Kabardinka 2, (b3) Levinsadovka-Saf’janovo.