Scolecite

This large sample of scolecite is displayed in the Smithsonian Museum of Natural History. It is about 50 cm across and is from Nasik, Maharashtra, India. Each elongated needle is a crystal whose shape reflects the chainlike arrangement of its atoms. The cluster grew from a water solution that filled a gas bubble in cooled volcanic rock. Workers discovered it while quarrying. Scolecite is a silicate mineral with the composition CaAl₂Si₃O₁₀.3H₂O