Pectolite is a white to gray mineral, NaCa2Si3O8(OH), sodium calcium inosilicate hydroxide. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specific gravity of 2.7 to 2.9. The gemstone variety, larimar is a pale to sky blue.
It was first described in 1828 at Mt. Baldo, Trento Province, Italy. It is found in basaltic rocks associated with various zeolites, prehnite, calcite, datolite, sugilite, fluorite, and serpentine. It is found in a wide variety of worldwide locations.