Pectolite

Pectolite 3.5×3.0x1.8 cm Jeffrey Mine Asbestos Quebec, Canada Copyright © David K. Joyce Minerals
Chemical Formula: NaCa2(HSi3O9)
Locality: Prospect Park quarry, northern New Jersey.
Name Origin: From the Greek pektos – “compacted” and lithos – “stone.”Pectolite is a white to gray mineral, NaCa2(HSi3O9), sodium calcium inosilicate hydroxide. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specific gravity of 2.7 to 2.9. The gemstone variety, larimar, is a pale to sky blue.

Occurrence

It was first described in 1828 at Mt. Baldo, Trento Province, Italy and named from the Greek pektos – “compacted” and lithos – “stone”.

It occurs as a primary mineral in nepheline syenites, within hydrothermal cavities in basalts and diabase and in serpentinites in association with zeolites, datolite, prehnite, calcite and serpentine. It is found in a wide variety of worldwide locations.

History

Discovery date : 1828
Town of Origin : MT. BALDO et MT. MONZONI
Country of Origin : ITALIE

Optical properties

Optical and misc. Properties: Transparent  –   Translucide  –   Luminescent, fluorescent  –   Gemme, pierre fine  –   Opaque  –   Macles possibles  –   Triboluminescent  –   Fragile, cassant  –   Tenace  –
Refractive Index: from 1,59 to 1,64
Axial angle 2V: 50-63°

Physical properties

Hardness : from 4,50 to 5,00
Density: from 2,84 to 2,90
Color : colorless; white; grey white; whitish; grayish; grey; pink; green; red; yellowish
Luster : subvitreous; silky; nacreous
Streak: white
Break : conchoidal; irregular
Cleavage: Yes

Photos:

Pectolite 5.6×3.2×4.1 cm Jeffrey Mine Asbestos Quebec, Canada Copyright © David K. Joyce Minerals
Pectolite 3.4×2.9×2.8 cm Jeffrey Mine Asbestos Quebec, Canada Copyright © David K. Joyce Minerals
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