pectolite

{{infobox mineral | name = Pectolite | category = Inosilicate mineral | image = Pectolite-263712.jpg | imagesize = 260px | caption = | formula = NaCa2Si3O8(OH) | IMAsymbol = Pct | molweight = | strunz = | dana = | system = Triclinic | class = Pinacoidal () (same H-M symbol) | symmetry = P | 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 | color = Colorless, whitish, grayish, yellowish | colour = | habit = Tabular to acicular, radiating fibrous, spheroidal, or columnar; massive | twinning = Twin axis [010] with composition plane [100], common | cleavage = Perfect on {100} and {001} | fracture = Uneven | tenacity = Brittle; tough when compact | mohs = 4.5 – 5 | luster = Silky, subvitreous | streak = White | diaphaneity = Translucent to opaque | gravity = 2.84 – 2.90 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.594 – 1.610 nβ = 1.603 – 1.614 nγ = 1.631 – 1.642 | birefringence = δ = 0.037 | pleochroism = | 2V = Measured: 50° to 63°, Calculated: 42° to 60° | dispersion = r > v weak to very strong | extinction = | length fast/slow = | fluorescence= | other = | alteration = | references = }} Pectolite is a white to gray mineral, NaCa2Si3O8(OH), a 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. A highly sought-after variety known as larimar, is a pale to sky blue. There is also a whitish form of the mineral from Alaska that is sometimes marketed as 'Alaska jade'.

==Occurrence== thumb|left| Pectolite var. Larimar It was first described in 1828 at Mount Baldo, Trento Province, Italy, and named from the Greek pektos – "compacted" and lithos – "stone".