What is Pectolite?
Pectolite is a delicate calcium sodium silicate best known as the mineral basis of blue Larimar from the Dominican Republic.
Mineralogy and crystal structure
Reference formula: NaCa2Si3O8(OH). Pectolite is triclinic and commonly fibrous. Blue Larimar is a distinctive copper-bearing pectolite variety, so the page is the scientific parent for a major commercial stone. Pectolite is classified with silicates and has a triclinic crystal system. Typical hardness is 4.5–5 on the Mohs scale and specific gravity is approximately 2.8–2.9.
Colour, lustre and habit
Typical colours include white, colourless, pale blue, grey. The usual acicular, radiating, fibrous habit and vitreous, silky, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Pectolite forms in or is associated with basalt cavities, hydrothermal veins and alkaline volcanic environments. Important documented localities include Dominican Republic, Canada, the United States, England and Germany.
The mineral behind Larimar
Pectolite gives Larimar its scientific anchor. The same triclinic mineral can appear as fragile white sprays or as blue patterned lapidary material.
Collecting and care
Protect fibres and polished Larimar from scratches, heat and acids; do not soak porous or heavily fractured material.
