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Pectolite

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Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, Rouville RCM, Montérégie, Québec, Canada

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Formula:
NaCa
 
2
(HSi
 
3
O
 
9
)
System:TriclinicColour:Colourless, white, pale ...
Hardness:4½ - 5
Member of:Wollastonite Group
Name:From the Greek for compact, in allusion to its resistance to pulverization.


Wollastonite Group.
Pectolite-Sérandite Series. The calcium analogue of Sérandite.

Classification of Pectolite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/F.18-60
Nickel-Strunz 10th (pending) edition ID:9.DG.05

9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
Dana 8th edition ID:65.2.1.4a

65 : INOSILICATES Single-Width,Unbranched Chains,(W=1)
2 : Single-Width Unbranched Chains, W=1 with chains P=3
Hey's CIM Ref.: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

Co-type Localities:Monzoni Mts, Fassa Valley, Trento Province, Trentino-Alto Adige, Italy
Sano, Mori, Mt. Baldo, Trento Province, Trentino-Alto Adige, Italy
Year of Discovery:1828

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

Lustre: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 (measured):2.84 - 2.9 g/cm3
Density (calculated):2.87 g/cm3

Crystallography of Pectolite

Crystal System:Triclinic
Class (H-M):1 - Pinacoidal
Space Group:P1
Cell Parameters:a = 7.99Å, b = 7.03Å, c = 7.03Å
α = 90.51°, β = 95.21°, γ = 102.53°
Ratio:a:b:c = 1.137 : 1 : 1
Unit Cell Volume:V 383.71 ų (Calculated from Unit Cell)
Z:2
Morphology:Crystals tabular, acicular. Radiating fibrous, spheroidal, columnar, fine-grained, massive.
Twinning:Common with twin axis [010], composition plane {100}
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
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°
Maximum Birefringence:δ = 0.037

Chart 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:
NaCa
 
2
(HSi
 
3
O
 
9
)
Essential elements:Ca, H, Na, O, Si
All elements listed in formula:Ca, H, Na, O, Si
Common Impurities:K,Fe,Mg,Al,H2O

Relationship of Pectolite to other Species

Series:Forms a series with Sérandite (see here)
Member of:Wollastonite Group
Other Members of Group:

- +
Bustamite
CaMn
2+
 
(Si
 
2
O
 
6
)
Ferrobustamite
Ca(Fe
2+
 
,Ca,Mn
2+
 
)(Si
 
2
O
 
6
)
Sérandite
Na(Mn
2+
 
,Ca)
 
2
(HSi
 
3
O
 
9
)
Tanohataite
LiMn
 
2
(HSi
 
3
O
 
9
)
Wollastonite
CaSiO
 
3
Related Minerals - Nickel-Strunz Grouping):

- +
9.DG.05Bustamite
CaMn
2+
 
(Si
 
2
O
 
6
)
9.DG.05Ferrobustamite
Ca(Fe
2+
 
,Ca,Mn
2+
 
)(Si
 
2
O
 
6
)
9.DG.05Sérandite
Na(Mn
2+
 
,Ca)
 
2
(HSi
 
3
O
 
9
)
9.DG.05Wollastonite
CaSiO
 
3
9.DG.05Wollastonite-1A
CaSiO
 
3
9.DG.07Cascandite
Ca(Sc,Fe
3+
 
)(HSi
 
3
O
 
9
)
9.DG.08Plombièrite
Ca
 
5
(HSi
 
3
O
 
9
)
 
2
 · 7H
 
2
O
9.DG.10Clinotobermorite
Ca
 
5
(Si
 
6
O
 
17
) · 5H
 
2
O
9.DG.10Riversideite
Ca
 
5
(HSi
 
3
O
 
9
)
 
2
 · 2H
 
2
O
9.DG.10Tobermorite
Ca
 
4+x
(H
 
2-2x
Si
 
6
O
 
17
) · 5H
 
2
O
9.DG.15Foshagite
Ca
 
4
(Si
 
3
O
 
9
)(OH)
 
2
9.DG.20Jennite
Ca
 
9
(Si
 
3
O
 
9
)
 
2
(OH)
 
8
 · 8H
 
2
O
9.DG.25Paraumbite
K
 
3
Zr
 
2
H(Si
 
3
O
 
9
)
 
2
 · nH
 
2
O
9.DG.25Umbite
K
 
2
(Zr,Ti)Si
 
3
O
 
9
 · H
 
2
O
9.DG.30Sørensenite
Na
 
4
SnBe
 
2
Si
 
6
O
 
16
(OH)
 
4
9.DG.35Xonotlite
Ca
 
6
(Si
 
6
O
 
17
)(OH)
 
2
9.DG.40Hillebrandite
Ca
 
2
(SiO
 
3
)(OH)
 
2
9.DG.45Zorite
Na
 
8
(Ti,Nb)
 
5
(Si
 
6
O
 
17
)
 
2
(OH,O)
 
5
 · 14H
 
2
O
9.DG.45Chivruaiite
Ca
 
4
(Ti,Nb)
 
5
(Si
 
6
O
 
17
)
 
2
(OH,O)
 
5
 · 13-14H
 
2
O
9.DG.50Haineaultite
(Na,Ca)
 
5
Ca(Ti,Nb)
 
5
(Si
 
6
O
 
17
)
 
2
(OH,F)
 
8
 · 5H
 
2
O
9.DG.55Epididymite
Na
 
2
Be
 
2
Si
 
6
O
 
15
 · H
 
2
O
9.DG.60Eudidymite
Na
 
2
Be
 
2
Si
 
6
O
 
15
 · H
 
2
O
9.DG.65Elpidite
Na
 
2
ZrSi
 
6
O
 
15
 · 3H
 
2
O
9.DG.70Fenaksite
(K,Na)
 
4
(Fe,Mn)
 
2
(Si
 
4
O
 
10
)
 
2
(OH,F)
9.DG.70Litidionite
CuNaKSi
 
4
O
 
10
9.DG.70Manaksite
KNaMnSi
 
4
O
 
10
9.DG.75Tinaksite
K
 
2
Na(Ca,Mn
2+
 
)
 
2
Ti[O|Si
 
7
O
 
18
(OH)]
9.DG.75Tokkoite
K
 
2
Ca
 
4
Si
 
7
O
 
17
(O,OH,F)
 
4
9.DG.75Senkevichite
CsKNaCa
 
2
Ti[O|Si
 
7
O
 
18
(OH)]
9.DG.80Canasite
K
 
2
Na
 
4
Ca
 
5
(Si
 
12
O
 
30
(OH,F)
 
4
9.DG.80Fluorcanasite
K
 
3
Na
 
3
Ca
 
5
Si
 
12
O
 
30
F
 
4
 · H
 
2
O
9.DG.85Miserite
K(Ca,Ce)
 
4
Si
 
5
O
 
13
(OH)
 
3
9.DG.90Frankamenite
K
 
3
Na
 
3
Ca
 
5
(Si
 
12
O
 
30
)(F,OH)
 
4
 · H
 
2
O
9.DG.92Charoite
(K,Na)
 
6-7
(Ca,Na)
 
18
[(Si
 
6
O
 
17
)(Si
 
12
O
 
30
)(Si
 
18
O
 
45
)](OH,F)
 
2
 · n H
 
2
O
9.DG.95Yuksporite
(K,Ba)NaCa
 
2
(Si,Ti)
 
4
O
 
11
(F,OH) · H
 
2
O
9.DG.97Eveslogite
(Na,K,Ca,Sr,Ba)
 
48
 [(Ti,Nb,Mn,Fe
2+
 
)
 
12
Si
 
48
O
 
144
(OH)
 
12
](F,OH,Cl)
 
14
Related Minerals - Hey's Index Grouping:

- +
14.6.1Combeite
Na
 
2
Ca
 
2
(Si
 
6
O
 
18
)
 
0.5
14.6.3Pectolite-M2abc
NaCa
 
2
[HSi
 
3
O
 
9
]
14.6.4Denisovite
Ca
 
2
(K,Na)Si
 
3
O
 
8
(F,OH)
 
2
14.6.5Tokkoite
K
 
2
Ca
 
4
Si
 
7
O
 
17
(O,OH,F)
 
4
14.6.6Mountainite
KNa
 
2
Ca
 
2
[Si
 
8
O
 
19
(OH)] · 6H
 
2
O
14.6.7Rhodesite
KHCa
 
2
Si
 
8
O
 
19
 · 5H
 
2
O
14.6.8Miserite
K(Ca,Ce)
 
4
Si
 
5
O
 
13
(OH)
 
3
14.6.9Åkermanite
Ca
 
2
Mg(Si
 
2
O
 
7
)
14.6.10Monticellite
CaMgSiO
 
4
14.6.11Merwinite
Ca
 
3
Mg(SiO
 
4
)
 
2
14.6.12Diopside
CaMgSi
 
2
O
 
6
14.6.13Tremolite
☐{Ca
 
2
}{Mg
 
5
}(Si
 
8
O
 
22
)(OH)
 
2

Other Names for Pectolite

Synonyms:
Alaska JadeGonsogoliteOsmelitePecktolitePektolith
Stellite
Other Languages:
German:Gonsogolit
Osmelith
Pecktolit
Pectolit
Russian:Пектолит
Spanish:Gonsogolita
Pecktolita
Pectolita
Varieties:
LarimarManganoan Pectolite

Polytypes for Pectolite

Polytypes:
Pectolite-M2abc

Other Information

Other Information:May be triboluminescent.
Health Warning: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:

- +
American Mineralogist (1978): 63: 427.

Zeitschrift für Kristallographie: 108: 248-262.

Zeitschrift für Kristallographie: 125: 298-316.

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

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Pectolite details from Handbook of Mineralogy (PDF)
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