Tobermorite

Not to be confused with torbernite, a hydrated copper uranyl phosphate.

Tobermorite is a calcium silicate hydrate mineral with chemical formula: Ca₅Si₆O₁₆(OH)₂·4H₂O or Ca₅Si₆(O,OH)₁₈·5H₂O.

Two structural varieties are distinguished: tobermorite-11 Å and tobermorite-14 Å. Tobermorite occurs in hydrated cement paste and can be found in nature as alteration mineral in metamorphosed limestone and in skarn. It has been reported from the Maqarin Area of north Jordan and in the Crestmore Quarry near Crestmore Heights, Riverside County, California.