pectolite

{{Short description|Silicate mineral}}

{{infobox mineral

| name = Pectolite

| category = Inosilicate mineral

| image = Pectolite-263712.jpg

| imagesize = 260px

| caption =

| formula = NaCa₂Si₃O₈(OH)

| IMAsymbol = Pct{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}

| molweight =

| strunz =

| dana =

| system = Triclinic

| class = Pinacoidal ({{overline|1}})
(same H-M symbol)

| symmetry = P{{overline|1}}

| 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 = n_α = 1.594 – 1.610 n_β = 1.603 – 1.614 n_γ = 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 = [http://rruff.geo.arizona.edu/doclib/hom/pectolite.pdf Handbook of Mineralogy][http://www.mindat.org/show.php?id=3141&ld=1&pho= Mindat w/ localities][http://webmineral.com/data/Pectolite.shtml Webmineral]

}}

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'.