Fig. 7

XRD test results for (a) calcined POLA and (b) calcined PLA. Note: Q = Quartz (SiO₂), M = Mullite (Al₆Si₂O₁₃), Ca = Calcite (CaCO₃), P = Periclase (MgO), Cr = Cristobalite (SiO₂ – high-temperature), An = Anhydrite (CaSO₄), H = Hematite (Fe₂O₃).