Scolecite is a tectosilicate mineral belonging to the zeolite group; it is a hydrated calcium silicate, CaAl2Si3O10·3H2O. Only minor amounts of sodium and traces of potassium substitute for calcium. There is an absence of barium, strontium, iron and magnesium.[1][5] Scolecite is isostructural (having the same structure) with the sodium-calcium zeolite mesolite and the sodium zeolite natrolite, but it does not form a continuous chemical series with either of them.[1] It was described in 1813, and named from the Greek word, σκώληξ (sko-lecks) = "worm" because of its reaction to the blowpipe flame.
There is no type locality. Most of the world's finest scolecite specimens are found in the Tertiary Deccan Basalt near Nasik, Pune, in the state of Maharashtra, India. The quarries in the Nasik region produce large, colourless sprays of well terminated coarse scolecite crystals that are commonly twinned on {100} to form V-shaped terminations with V-shaped striations on {010}. The scolecite is commonly found alone or on stilbite and is covered with laumontite or colourless, pale green or white fluorapophyllite. It is also found in the region as massive radiating material with powellite, and in cavities in basalt as colourless, flattened crystals in radiating sprays on blocky green apophyllite covered by tiny, thin, colourless apophyllite plates.[5]
