Table 1: X-ray Analyses for gray and red Erzurum clay.

CompoundGrey clay (%)Red clay (%)

SiO255.3658.17
Al2O311.0613.22
Fe2O35.8510.06
CaO8.65.39
MgO3.01.52
0.490.09
Na2O2.71.74
K2O2.410.23
Cl0.16