Mountainite Mineral Data

Mountainite Mineral Data +

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General Mountainite Information

Chemical Formula:

(Ca,Na2,K2)2Si4O10·3(H2O)

Composition:

Molecular Weight = 409.00 gm

Potassium 4.78 % K 5.76 % K₂O

Sodium 5.62 % Na 7.58 % Na₂O

Calcium 9.80 % Ca 13.71 % CaO

Silicon 27.47 % Si 58.76 % SiO₂

Hydrogen 1.48 % H 13.21 % H₂O

Oxygen 50.85 % O

______ ______

100.00 % 99.02 % = TOTAL OXIDE

Empirical Formula:

NaCaK_0.5Si₄O₁₀·3(H₂O)

Environment:

Intrusive kimberlite and differentiated alkalic massif (Lovozero, Russia).

IMA Status:

Valid Species (Pre-IMA) 1957

Locality:

In a kimberlite pipe at Kimberley, South Africa. Link to MinDat.org Location Data.

Name Origin:

Named for Edgar Donald Mountain, Professor of Geology, Rhodes University, Grahamstown, South Africa.

Mountainite Image

Images:

Mountainite Raite

Comments: Bright white fibrous acicular mountainite crystal aggregate with pale golden raite.
Location: Lovozero Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Mountainite Crystallography

Axial Ratios:

a:b:c =2.0625:1:2.0625

Cell Dimensions:

a = 13.51, b = 6.55, c = 13.51, Z = 4; beta = 104° V = 1,160.00 Den(Calc)= 2.34

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/a,P 2₁/c,P 2₁/n

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.94(1), 6.6(0.8), 4.67(0.7),13.1(0.7), 1.967(0.6), 2.8(0.6), 4.18(0.5),

Physical Properties of Mountainite

Cleavage:

[001] Distinct

Color:

White.

Density:

2.36

Diaphaniety:

Transparent to Translucent

Habit:

Felted - Occurs as minute crystalling aggregates with the form of felt material.

Habit:

Lath - Shaped like a small, thin plaster lath, tabular (rectangular) in shape.

Habit:

Rosette - Bundled tabular aggregates resembling rose flower petals.

Luster:

Silky

Streak:

white

Optical Properties of Mountainite

Gladstone-Dale:

CI meas= 0.028 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.019 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2173,KPDmeas= 0.2155,KC= 0.2216

Optical Data:

Biaxial (+), a=1.5-1.504, b=1.505-1.51, g=1.513-1.519, bire=0.0130-0.0150, 2V(Calc)=78-80, 2V(Meas)=moderate.

Calculated Properties of Mountainite

Electron Density:

r_electron=2.36 gm/cc
note: r_Mountainite=2.34 gm/cc.

Fermion Index

Fermion Index = 0.01321
Boson Index = 0.98679

Photoelectric:

PE_Mountainite= 2.84 barns/electron
U=PE_Mountainite x r_electron= 6.70 barns/cc.

Radioactivity:

GRapi = 69.63 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Mountainite - barely detectable

Mountainite Classification

Dana Class:

77.2.3.1 (77)Tectosilicate Zeolite group

(77.2)related species

(77.2.3)Dana Group

77.2.3.1 Mountainite (Ca,Na2,K2)2Si4O10·3(H2O) P 2₁/a,P 2₁/c,P 2₁/n 2/m

Strunz Class:

VIII/H.15-30 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like layered silicates with [Si4O10]4- and related groups

VIII/H.15 - Agrellite - Mountainite series

VIII/H.15-10 Agrellite NaCa2Si4O10F P1 1

VIII/H.15-20 Glagolevite! NaMg6[Si3AlO10](OH,O)8·H2O C1 1

VIII/H.15-30 Mountainite (Ca,Na2,K2)2Si4O10·3(H2O) P 2₁/a,P 2₁/c,P 2₁/n 2/m

Other Mountainite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(AntBidBlaNic2)

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Mountainite

(Ca,Na2,K2)2Si4O10·3(H2O)
Dana No: 77.2.3.1 Strunz No: VIII/H.15-30
Locality:

Notes: