Pectolite

NaCa₂(HSi₃O₉)

These samples of pectolite are displayed in the Smithsonian Museum of Natural History. Pectolite is an silicate mineral of calcium and sodium. It has the composition NaCa₂(HSi₃O₉). The rounded specimen has a diameter of about 11 cm wide and is from Prospect Park, New Jersey.

From the museum's description: "The rounded shape of pectolite comes from many crystals crowding together like seeds on a dandelion. You can see some in the broken area of the specimen. The other rounded, or botryoidal, specimens formed in much the same way."

Mindat: Pectolite