silicates
Pectolite
NaCa2Si3O8(OH)
- Also known as
- larimar
- Crystal system
- triclinic
- Hardness
- 4.5–5 on the Mohs scale
- Lustre
- silky
- Colour
- White, grey, and blue as larimar
- Where it forms
- In cavities in basalt, and in the Dominican case in volcanic rock where copper-rich fluids were involved.
- Chiefly from
- New Jersey, United StatesBarahona, Dominican RepublicCanada
Why it is that colour
Copper substituting for calcium gives the blue of larimar. Ordinary pectolite is white or grey.
Safety
Safe to handle. Pectolite frequently forms as radiating needles, and needle-like fragments should not be inhaled or handled carelessly; the massive larimar form is not an issue.
Where it comes from
Ordinary pectolite is a common specimen mineral. The blue variety is confined to one small area of the Dominican Republic.
Historical use
Named in 1828 from the Greek for compacted. Of no economic significance except through larimar.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
Worth knowing
Pectolite is here as the parent of larimar, and to make the same point that lazurite makes for lapis and zoisite for tanzanite: the material people buy usually has a mineral behind it with a duller name and a longer entry in the literature.
Identity checked against IMA-CNMNC master list, June 2025.