Table 4 Chemical composition of different mixtures of M2-D2 diatomite specimens after firing at 1100 °C for 1 h

SiO₂

65.77

62.15

56.70

52.44

48.27

Al₂O₃

10.94

10.41

9.62

9.00

8.39

Fe₂O₃

6.78

6.66

6.49

6.33

6.19

MnO

0.04

0.05

0.05

0.059

0.06

MgO

1.76

1.80

1.86

1.89

1.93

CaO

10.35

14.57

21.31

25.88

30.75

Na₂O

0.55

0.63

0.75

0.82

0.91

K₂O

1.22

1.16

1.09

1.02

0.96

TiO₂

0.89

0.87

0.85

0.83

0.80