Oxides

Minimum

Maximum

Average

SiO₂

47.84

70.45

61.81

Al₂O₃

6.32

17.42

13.07

TiO₂

0.12

0.94

0.36

MnO

0.44

3.36

1.45

Fe₂O₃

1.20

13.11

5.79

FeO

0.10

0.51

0.27

P₂O₅

0.40

1.45

0.70

CaO

1.25

25.61

8.80

MgO

0.86

7.90

3.52

Na₂O

0.34

2.84

1.55

K₂O

0.02

5.94

2.12

H₂O⁺

0.30

0.96

0.52