Scolecite mineral. Scolecite is a hydrated calcium silicate (Ca.Al2.Si3.O10.3[H2O]). It is tectosilicate mineral, part of zeolite group. It is monoclinic but the habitat is pseudo-tetragonal, with crystals occurring in fibrous aggregations that are often radially arranged. Its colour is colourless white to pinkish-red or very light green. Scolecite looks very similar to the closely related zeolite minerals natrolite and mesolite. This sample, from Poona in India, measures 12 centimetres across.