Thomsonite

This sample of Thomsonite is displayed in the Smithsonian Museum of Natural History. Thomsonite is classified as part of the zeolite group of silicate minerals, containing 5 of the Big 8 elements. It has the composition NaCa₂(Al₅Si₅)O₂₀.6H₂O This sample is about 12x5 cm and is from Grand Marais, Minnesota.