Chemical composition -- A hydrated sodium calcium silicate with manganese.
Color -- Blue-green, white, gray.
Optics -- R.I . 1.60-1.64 (usually spot reading of 1.60). Biaxial positive. Vitreous (glassy) to silky luster.
Durability -- Hardness 4.5-5. Splintery fracture and perfect cleavage in one direction.
Crystal structure -- Triclinic.
Specific Gravity -- 2.74-2.88.
Sources -- Dominican Republic, Canada (Quebec), U.S.A. (New Jersey, Alaska, California)).
The best known source is the Dominican Republic, from whence fine copper-colored blue material is marketed under the tradename "Larimar." Larimar often has a characteristic white spider-veined or cellular appearance. Though locally abundant, fine pectolite is rather scarce.