Fibrous pectolite has long been a curiosity for gem collectors. Compact material can make wonderful cabochons, and transparent crystals are rare and usually tiny. In 1974, blue pectolite was found in the Dominican Republic. Known by the trade name Larimar, this blue gem has since become a popular jewelry stone.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Triclinic. Crystals acicular, radial or globular masses; often terminated.|
|Colors||Colorless, white, gray. (Larimar can range from dark blue to blue-green and sky blue).|
|Luster||Vitreous to silky.|
|Hardness||4.5-5. (Compact material can reach 6).|
|Cleavage||Perfect 1 direction.|
|Luminescence||See "Identifying Characteristics" below.|
|Transparency||Translucent to transparent. (Opaque to translucent, Larimar)|
|Formula||NaCa2Si3O8(OH) + Mn.|
|Optics||a = 1.595-1.610; β = 1.605-1.615; γ = 1.632-1.645. Biaxial (+), 2V = 50-63°. Refractometer spot reading at about 1.60. See “Identifying Characteristics” below.|
|Etymology||From the Greek pektos for “congealed,” because of the mineral's sometimes translucent appearance. Larimar is a combination of Lari, short for “Larissa,” and the Spanish mar for “sea.” Miguel Méndez and Norman Rilling discovered this blue pectolite variety in the Dominican Republic in 1974. Larissa was the name of Méndez's oldest daughter.|
|Occurrence||In cavities in basaltic rocks, associated with zeolites; in lime-rich metamorphic rocks.|
|Inclusions||Hematite can create fern-like “red plume” patterns, calcite crystals.|
Although the mineral pectolite occurs in locations across the globe, these fibrous aggregates are seldom cohesive enough to cut. This material is usually too soft and fragile for jewelry wear. However, if pectolite’s fibers inter-grow, it can become jade-like in toughness as well as appearance. When sufficiently compact, pectolite cabochons take an excellent polish.
Gem-quality pectolite comes mainly from Quebec, Canada and the Dominican Republic.
With colors ranging from white to various shades of blue, Dominican pectolite is the loveliest in the world. Traces of copper contribute to this blue coloration. The finest stones are dark blue and translucent. Known by the trade name Larimar, this variety of compact pectolite can take a very high polish. Though locally abundant, Larimar is a rare gem material.
The refractive indices of this series vary with the presence of Ca and Mn.
Fibrous material has chatoyancy that can give pectolite cabochons a cat’s eye effect.
In longwave (LW) ultraviolet light:
- Orange-pink (Bergen Hill, New Jersey).
- Cream white (Lendalfoot, Scotland).
In shortwave (SW) ultraviolet light:
- Greenish yellow (Scotland).
- Yellowish, orange with green areas (Magnet Cove, Arkansas and Lake County, California).
- Faint yellow with phosphorescence (Paterson, New Jersey).
Although no known pectolite synthetics exist, simulants have surfaced. These include ceramics and glass, such as “Victoria Stone” and “Imori Stone.” However, a gemological analysis can easily identify these.
No known common gem treatments.
In addition to the Dominican Republic, other notable sources include:
- Canada: Thetford Mines and Asbestos, Quebec, produce magnificent, prismatic crystals, the only sources of facetable pectolite. Twinned crystals up to 5” long, colors range from white to pale blue-green.
- Alaska: massive, jade-like stones (used as a jade substitute); also fine-grained, pale blue-green.
- Magnet Cove, Arkansas: pinkish manganiferous material.
- Lake Count, California: dense material suited for cabochons.
- New Jersey; Paterson area, in fine radial sprays: also at Franklin and Sterling Hill.
- Greenland: manganiferous material.
- Czech Republic; Japan; Morocco; Russia; Scotland; Sweden; South Africa.
Lapidaries have cut cabochons up to a few inches from dense, massive, or fibrous material. Small, faceted gems mined in 1973 from Asbestos, Quebec range in size up about 3 carats. Only a few stones have been faceted.
Although some pectolite stones, especially Larimar, are relatively tough, their hardness range (from 4.5 to 6) makes them susceptible to scratches. Popular jewelry stones, such as quartz, topaz, corundum, and diamond, will scratch them. So, store your pectolite jewelry separately from such pieces. Use protective settings for rings. Pectolite cabs make excellent stones for pendants and earrings. Clean your gems and jewelry pieces with a soft brush, mild detergent, and warm water. Consult our gemstone jewelry cleaning guide for more recommendations.