Oxide

Sample

F-09-12^a

Grey gneisses^b

Oxide content, wt. %

SiO₂

66.19

67.67

TiO₂

0.72

0.44

Al₂O₃

16.49

14.87

FeO_t

5.82

3.58

MnO

0.06

0.07

MgO

0.44

1.86

CaO

1.69

3.35

Na₂O

3.06

4.18

K₂O

1.97

2.60

Total

96.44

98.62