Chemical composition (% by mass)^*

SiO₂

Al₂O₃

Fe₂O₃

TiO₂

CaO

MgO

Na₂O

K₂O

SO₃

Cl⁻

Loss of ignition

FR1

80.50

2.32

1.30

0.12

0.85

4.25

4.60

0.74

4.84

0.45

14.62

FR2

92.3

3.83

0.49

0.05

2.05

0.19

0.01

0.05

0.23

3.23

3.23