Chemical elements

Grey clays

Yellow clays

Chemical composition (%)

SiO₂

76.833

72.394

Al₂O₃

12.552

12.270

Fe₂O₃

2.619

4.930

TiO₂

1.042

0.973

CaO

0.235

0.253

MgO

0.875

0.750

K₂O

1.560

1.470

Na₂O

0.495

0.820

H₂O or loss on ignition

4.225

4.980