Scolecite is a hydrated calcium aluminium silicate, CaAl2Si3O10.3H2O, a tectosilicate mineral belonging to the zeolite group. It is monoclinic, but crystals are pseudotetragonal, usually occurring as acicular needles in fibrous aggregations. The orange red substrate in this sample is heulandite, also a tectosilicate mineral in the zeolite group. Sample is from extrusive rocks near the city of Pune (formerly Poona) in India; sample width is 150 mm.