Category Inosilicate mineral Crystal system Triclinic | Formula
(repeating unit) NaCa2Si3O8(OH) Space group P1 | |
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Crystal class Pinacoidal (1)
(same H-M symbol) Unit cell a = 7.99 Å, b = 7.03 Å,
c = 7.03 Å; α = 90.51°,
β = 95.21°, γ = 102.53°; Z = 2 | ||
Pectolite is a white to gray mineral, NaCa2Si3O8(OH), sodium calcium hydroxide inosilicate. 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.
References
Pectolite Wikipedia(Text) CC BY-SA