Saponite

Saponite is a trioctahedral mineral of the smectite group. Its chemical formula is Ca0.25(Mg,Fe)3((Si,Al)4O10)(OH)2·n(H2O). It is soluble in sulfuric acid. It was first described in 1840 by Svanberg. Varieties of saponite are griffithite, bowlingite and sobotkite.