Component

Content in wt.%

SiO₂

90.9

Al₂O₃

1.9

Fe₂O₃

1.5

CaO

0.5

MgO

0.3

K₂O,TiO₂, SO₃, Cl, MnO, ZnO, CuO, NiO,Cr₂O₃, SrO, BaO

each < 0.1

H₂O

4.7