Pectolite
Species
Uncommon · NaCa₂Si₃O₈(OH)
Needle sprays lining cavities in basalt and serpentinite; compact masses are so hard to crush that the name comes from the Greek for held tightly together. Its blue Dominican variety, larimar, is the pectolite best known as a gemstone.
Identity
- Formula
- NaCa₂Si₃O₈(OH)
- Chemical class
- Silicate
- Varieties
- Larimar
- Mineral group
- Rhodonite
- Also known as
- Larimar (blue variety)
Crystallography
- Crystal system
- Triclinic
- Habits
- Acicular, Fibrous, Massive
- Fracture
- Uneven
Physical properties
- Mohs hardness
- 5
- Density
- 2.86 g/cm³
- Luster
- Silky, Vitreous
- Colors
- white, gray, light pink, light green
- Streak
- white
- Transparency
- Translucent, Opaque
Geology
- Origins
- Igneous, Hydrothermal
- Host rocks
- Volcanic rock, Ultramafic rock (peridotite, serpentinite)
- Associated minerals
- Prehnite, Calcite, Natrolite, Analcime
- Geography
- Dominican Republic, Canada, USA
Classification
- Rarity
- Uncommon
- Gem quality
- Yes
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- Pectolite. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Pectolite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
Browse the Crystal Encyclopedia — MGS Toolbox