Okenite (CaSi2O5·2H2O) is a silicate mineral. It most commonly is found as small white "cotton ball" formations within basalt. These formations are clusters of straight, radiating, fibrous crystals that are both bendable and fragile. It also belongs to the family of the calcium silicate hydrates (C-S-H) commonly found in hardened cement paste. In cement chemist notation (CCN) it is noted as CaO·2SiO2·2H2O and abbreviated as CS2H2.