Spot No.

1

2

3

4

Major oxides wt% recalculated to 100%

SiO₂

32.19

30.38

38.27

30.97

TiO₂

0.011

0.002

0.18

0.002

Al2O₃

20.23

19.43

17.58

20.33

FeO*

27.15

30.12

25.22

28.34

MgO

18.26

16.87

16.89

16.62

CaO

0.018

0.017

0.519

0.418

Na₂O

2.24

3.21

1.32

3.32

K₂O

0.011

0.012

0.012

0.011

Total

100

100

100

100

Cations on basis of 32 oxygens

Si

4.68

4.45

5.65

4.54

Ti

0.011

0.01

0.389

0.011

Al

3.07

2.97

2.539

3.12

Al

2.05

1.98

2.009

2.74

Al

1.05

0.98

0.531

0.48

Fe

3.44

3.69

2.74

3.57

Mg

3.98

3.68

1.72

3.69

Ca

0.001

0.001

0.08

0.07

Na

0.64

0.91

0.38

0.95

K

0.001

0.001

0.001

0.002