Larimar
Last updated: April 2026
The blue gem variety of pectolite, found only in the Los Chupaderos mine area of Barahona Province, Dominican Republic. The blue color derives from copper substituting for calcium in the crystal structure. Sky blue to blue-green with white patterns created by radiating fibrous crystal structure.
Physical & Optical Properties
RI Range1.595–1.640
SG Range2.74–2.90
SG Typical2.80
Hardness (Mohs)4.5–5
Crystal SystemTriclinic
Optic CharacterDR Biaxial (+)
Birefringence0.040
Dispersion0.010
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsBlue Violet
SpeciesPectolite
VarietyLarimar (Blue Pectolite)
Key Differentiators
- Sky blue color with distinctive white radiating or cloud-like patterns unique to pectolite
- Low hardness 4.5–5 — easily scratched with a knife blade
- Exclusively from Barahona Province, Dominican Republic — single world locality
- Silky fibrous radiating texture visible under loupe
- Lower RI (1.595–1.640) and different texture vs blue turquoise (1.610–1.650)
Common Simulants
- Blue Turquoise: Turquoise has waxy luster, no fibrous radiating texture, RI 1.610–1.650, SG 2.60–2.85. Lacks the pectolite radiating pattern.
- Blue Calcite: Calcite SG ~2.71, lower hardness (3), effervesces with acid, RI 1.486–1.658 with extreme birefringence.
- Blue Glass: Glass lacks fibrous texture, isotropic under polariscope, SG varies widely, typically cold to touch.
- Dyed Howlite: Dyed howlite shows dye in cracks under loupe, acetone removes dye, SG ~2.53, hardness only 3.5, strong LW fluorescence in undyed areas.
Treatments
- Wax or Resin Impregnation (surface stabilization)
Price Context
Natural — low ($/ct)$10
Natural — high ($/ct)$500
NotePer carat; standard blue $10–100/ct; fine sky blue $50–200/ct; rare deep 'volcano blue' $100–500/ct; cabochons and carvings are standard cut
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a larimar? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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