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Pectolite

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Formula:
NaCa2Si3O8(OH)
System:
Triclinic
Colour:
Colourless, white, pale ...
Hardness:
4½ - 5
Name:
Named in 1828 by Franz von Kobell from the Greek πηκτοζ for "well put together", in allusion to its resistance to pulverization.

Classification of Pectolite

Approved, 'Grandfathered' (first described prior to 1959)
9.DG.05

9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
65.2.1.4a

65 : INOSILICATES Single-Width,Unbranched Chains,(W=1)
2 : Single-Width Unbranched Chains, W=1 with chains P=3
14.6.2

14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
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Type Occurrence of Pectolite

Occurrences of Pectolite

Geological Setting:
Primary mineral in nepheline syenites. Hydrothermal mineral in cavities in basalts and diabases. In serpentinites and peridotites.

Physical Properties of Pectolite

Sub-Vitreous, Silky
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Colourless, white, pale pink, greenish, pale blue
Streak:
White
Hardness (Mohs):
4½ - 5
Tenacity:
Brittle
Cleavage:
Perfect
on {100} and {001}
Fracture:
Irregular/Uneven
Comment:
Tough when compact.
Density:
2.84 - 2.9 g/cm3 (Measured)    2.87 g/cm3 (Calculated)

Crystallography of Pectolite

Polytype:
Formula:
Crystal System:
Class (H-M)
Space Group:
Space Group Setting:
Cell Parameters:
Ratio:
Unit Cell Volume (calc):
Z:
Pectolite-1APectolite-M2abc
 NaCa2[HSi3O9]
Triclinic  
1 - Pinacoidal
P1 
  
a = 7.980(1) Å, b = 7.023(1) Å, c = 7.018(1) Å
α = 90.54(1)°, β = 95.14(1)°, γ = 102.55(1)°

a:b:c = 1.136 : 1 : 0.999 
V 382.20 ų
(Calculated from Unit Cell)
 
  
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Pectolite

Type:
Biaxial (+)
RI values:
nα = 1.594 - 1.610 nβ = 1.603 - 1.614 nγ = 1.631 - 1.642
2V:
Measured: 50° to 63°, Calculated: 42° to 60°
Max Birefringence:
δ = 0.037
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v weak to very strong

Chemical Properties of Pectolite

Formula:
NaCa2Si3O8(OH)
All elements listed in formula:
Common Impurities:
K,Fe,Mg,Al,H2O

Relationship of Pectolite to other Species

Series:
Forms a series with Sérandite (see here)
Other Members of Group:
Barrydawsonite-(Y)Na1.5Y0.5CaSi3O9H
BustamiteCaMn2+(Si2O6)
CascanditeCa(Sc,Fe3+)(HSi3O9)
FerrobustamiteCaFe2+(Si2O6)
MarshallsussmaniteNaCaMnSi3O8(OH)
SéranditeNaMn22+Si3O8(OH)
TanohataiteLiMn2(HSi3O9)
VistepiteSnMn4B2Si4O16(OH)2
WollastoniteCaSiO3
9.DG.05BustamiteCaMn2+(Si2O6)
9.DG.05FerrobustamiteCaFe2+(Si2O6)
9.DG.05SéranditeNaMn22+Si3O8(OH)
9.DG.05WollastoniteCaSiO3
9.DG.05Wollastonite-1ACaSiO3
9.DG.07CascanditeCa(Sc,Fe3+)(HSi3O9)
9.DG.08Plombièrite[Ca4Si6O16(OH)2 · 2H2O]·(Ca·5H2O)
9.DG.10Clinotobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)
9.DG.10RiversideiteCa5(HSi3O9)2 · 2H2O
9.DG.10Tobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)
9.DG.15FoshagiteCa4(Si3O9)(OH)2
9.DG.20JenniteCa9(Si3O9)2(OH)8 · 8H2O
9.DG.25ParaumbiteK3Zr2H(Si3O9)2 · nH2O
9.DG.25UmbiteK2(Zr,Ti)Si3O9 · H2O
9.DG.30SørenseniteNa4SnBe2Si6O16(OH)4
9.DG.35XonotliteCa6(Si6O17)(OH)2
9.DG.40HillebranditeCa2(SiO3)(OH)2
9.DG.45ZoriteNa8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2O
9.DG.45ChivruaiiteCa4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2O
9.DG.50Haineaultite(Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2O
9.DG.55EpididymiteNa2Be2Si6O15 · H2O
9.DG.60EudidymiteNa2Be2Si6O15 · H2O
9.DG.65ElpiditeNa2ZrSi6O15 · 3H2O
9.DG.70Fenaksite(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)
9.DG.70LitidioniteCuNaKSi4O10
9.DG.70ManaksiteKNaMnSi4O10
9.DG.75TinaksiteK2Na(Ca,Mn2+)2Ti[O|Si7O18(OH)]
9.DG.75TokkoiteK2Ca4[Si7O18(OH)](OH,F)
9.DG.75SenkevichiteCsKNaCa2Ti[O|Si7O18(OH)]
9.DG.80CanasiteK3Na3Ca5Si12O30(OH)4
9.DG.80FluorcanasiteK3Na3Ca5Si12O30F4 · H2O
9.DG.85MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O
9.DG.90FrankameniteK3Na3Ca5(Si12O30)(F,OH)4 · H2O
9.DG.92Charoite(K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O
9.DG.95YuksporiteK4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3
9.DG.97Eveslogite(Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14
14.6.1CombeiteNa2Ca2(Si6O18)0.5
14.6.3Pectolite-M2abcNaCa2[HSi3O9]
14.6.4DenisoviteCa2(K,Na)Si3O8(F,OH)2
14.6.5TokkoiteK2Ca4[Si7O18(OH)](OH,F)
14.6.6MountainiteKNa2Ca2[Si8O19(OH)] · 6H2O
14.6.7RhodesiteKHCa2Si8O19 · 5H2O
14.6.8MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O
14.6.9ÅkermaniteCa2Mg(Si2O7)
14.6.10MonticelliteCaMgSiO4
14.6.11MerwiniteCa3Mg(SiO4)2
14.6.12DiopsideCaMgSi2O6
14.6.13Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2

Other Names for Pectolite

Name in Other Languages:

Other Information

Other Information:
May be triboluminescent.
Health Risks:
The white needles of pectolite are sharp and stiff and easily penetrate the skin. Once embedded they are invisible and brittle and difficult to remove, often very painful. Handle with caution at all times. Do not rub your hands after handling. Rinse hands in a strong stream of water before handling anything else, especially food.

References for Pectolite

Reference List:
Peacock, M.A. (1935): On pectolite. Zeitschrift für Kristallographie, 90, 97–111.

Buerger, M.J. (1956): The determination of the crystal structure of pectolite, Ca2NaHSi3O9. Zeitschrift für Kristallographie, 108, 248–262.

Prewitt, C.T. (1967): Refinement of the structure of pectolite, Ca2NaHSi3O9. Zeitschrift für Kristallographie, 125, 298–316.

Takeuchi, Y. & Kudoh, Y. (1977): Hydrogen bonding and cation ordering in Magnet Cove pectolite. Zeitschrift für Kristallographie 146, 281-292.

American Mineralogist (1978): 63: 427.

Hammer, V.M.F., Libowitzky, E., and Rossman, G.R. (1998) Single-crystal IR spectroscopy of very strong hydrogen bonds in pectolite, NaCa2[Si3O4(OH)], and serandite, NaMn2[Si3O4(OH)]. American Mineralogist: 83: 569-576.

Internet Links for Pectolite

Specimens:
The following Pectolite specimens are currently listed for sale on minfind.com.

Localities for Pectolite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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