These samples of heulandite are displayed in the Smithsonian Museum of Natural History. Heulandite is a silicate mineral which can have a variety of metal ions (Ba,Ca,K,Na,Sr) It has the general composition (Ba,Ca,K,Na,Sr)5Al9Si27O72.22H2O. Besides the big-8 elements, it contains barium and strontium. The sample at left is described as heulandite with stilbite and quartz. It is about 5x17 cm and is from Berufjordur, Iceland. This particular sample is labeled with the composition (Ba,Ca,K,Na,Sr)5Al9Si27O72.26H2O.
This sample of heulandite is about 5x8 cm is from Teigarhorn, Berufjordur, Iceland.