Sample Constituents, %

Sample No.1

Sample No. II

Total SiO₂

65.30

67.86

Al₂O₃

18.65

16.84

Fe₂O₃

0.119

0.127

CaO

2.00

1.50

MgO

0.25

0.20

Na₂O

2.30

2.20

K₂O

10.97

10.92

L.O.I.

0.23

0.30