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Mountainite

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Formula:
KNa
 
2
Ca
 
2
[Si
 
8
O
 
19
(OH)] · 6H
 
2
O
System:MonoclinicColour:white
Hardness:3
Name:For Edgar Donald Mountain, Rhodes University, Grahamstown.


Closely related to cryptophyllite and shlykovite.

Classification of Mountainite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/H.15-30
Nickel-Strunz 10th (pending) edition ID:9.GG.10

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
G : Unclassified zeolites
Dana 8th edition ID:77.2.3.1

77 : TECTOSILICATES Zeolites
2 : Zeolite group - related species
Hey's CIM Ref.:14.6.6

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

Type Locality:Bultfontein, Lejweleputswa District, Free State Province, South Africa
General Appearance of Type Material:silky white fibers
Year of Discovery:1957
Geological Setting of type material:Kimberlite pipe
Associated Minerals at type locality:
Rhodesite

Physical Properties of Mountainite

Colour:white
Streak:white
Hardness (Mohs):3

Crystallography of Mountainite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:P2/b
Cell Parameters:a = 13.704(2) Å, b = 6.5760(10) Å, c = 13.751(2) Å
β = 105.752(10)°
Ratio:a:b:c = 2.084 : 1 : 2.091
Unit Cell Volume:V 1192.7 ų
Z:2

Optical Data of Mountainite

Type:Biaxial (+)
RI values: nα = 1.500 - 1.504 nβ = 1.505 - 1.510 nγ = 1.513 - 1.519
2V:Calculated: 78° to 80°
Maximum Birefringence:δ = 0.013 - 0.015

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:relatively strong

Chemical Properties of Mountainite

Formula:
KNa
 
2
Ca
 
2
[Si
 
8
O
 
19
(OH)] · 6H
 
2
O
Simplified for copy/paste:KNa2Ca2[Si8O19(OH)]·6H2O
Essential elements:Ca, H, K, Na, O, Si
All elements listed in formula:Ca, H, K, Na, O, Si
Common Impurities:Al,Mg,C

Relationship of Mountainite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.GG.05Cowlesite
CaAl
 
2
Si
 
3
O
 
10
· 6H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
14.6.1Combeite
Na
 
2
Ca
 
2
(Si
 
6
O
 
18
)
 
0.5
14.6.2Pectolite
NaCa
 
2
(HSi
 
3
O
 
9
)
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
14.6.7Rhodesite
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 Mountainite

Other Languages:
German:Mountainit
Spanish:Mountainita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Mountainite

Reference List:

- +
American Mineralogist (1958): 43: 624.

Doklady Akademii Nauk SSSR (1973): 210: 676.

Zubkova, N.V., I.V. Pekov, D.Yu. Pushcharovsky, N.V. Chukanov (2009): The crystal structure and refined formula of mountainite. Zeitschrift für Kristallographie 224, 389-396.

Internet Links for Mountainite

Search Engines:
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  • External Links:
  • Look for Mountainite on Webmineral
  • Look for Mountainite on Athena Mineralogy
  • Look for Mountainite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Mountainite details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
  • Rare and Unusual minerals at Mineralogical Research Company
  • Buy from McDougall Minerals
  • Fine and rare minerals from mintreasure.com
  • Find Mountainite on www.crystalclassics.co.uk
  • Buy RARE Minerals from Rocks of Africa
  • Fine minerals from bisbeeborn.com
  • Mineral Classics - Worldwide Collector Quality Minerals and Gems
  • Top quality minerals from Kristalle of California
  • High-end worldwide specimens & outstanding customer service
  • Search for Mountainite on Well-Arranged Molecules
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  • Localities for Mountainite

    The 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.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Germany
     
    • Baden-Württemberg
      • Hegau
        • Immendingen
    Tschernich, R. (1992), Zeolites of the World, p.42
    Romania
     
    • Hunedoara Co.
      • Hunedoara
    The Canadian Mineralogist Vol. 39, pp. 1405-1434 (2001)
    Russia
     
    • Northern Region
      • Murmanskaja Oblast'
        • Kola Peninsula
          • Lovozero Massif
            • Karnasurt Mt
    Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow; Zubkova, N. V., Pekov, I. V., Pushcharovsky, D. Y., & Chukanov, N. V. (2009). The crystal structure and refined formula of mountainite, KNa2Ca2 [Si8O19 (OH)]⊙ 6 H2O. Zeitschrift für Kristallographie, 224(8), 389-396.; Pluth, J. J., Smith, J. V., Pushcharovsky, D. Y., Semenov, E. I., Bram, A., Riekel, C., ... & Broach, R. W. (1997). Third-generation synchrotron x-ray diffraction of 6-μm crystal of raite,≈ Na3Mn3Ti0. 25Si8O20 (OH) 2⋅ 10H2O, opens up new chemistry and physics of low-temperature minerals. Proceedings of the National Academy of Sciences, 94(23), 12263-12267.
    South Africa
     
    • Free State Province
      • Lejweleputswa District
    Min.Mag.(1957) 31, 611-623; Minerals of South Africa
    USA
     
    • California
      • Trinity Co.
        • Klamath Mts
          • Trinity Mts
            • Halls Gulch District
              • Wildcat Peak
    Barnes, I., J.B. Rapp & J.R. O’Neil (1972), Metamorphic assemblages and the direction of flow of metamorphic fluids in four instances of serpentinization: Contributions to Mineralogy and Petrology: 35: 264; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 442; www.mineralsocal.org.
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    Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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