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Rhodesite

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Cecil Rhodes
Formula:
K2Ca2Si8O19 · 5H2O
System:
Orthorhombic
Colour:
White
Lustre:
Silky
Hardness:
3 - 4
Name:
Named after Cecil John Rhodes (1853-1902), British colonial statesman and financier of the Rhodes University, South Africa. He ran the British South Africa Company, which operated in a territory that bacame known as Rhodesia (named after him, now the countries of Zimbabwe and Zambia). He also found the De Beers diamond company. Do not confuse with Rhodizite.
Related to fivegite.


Classification of Rhodesite

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

9 : SILICATES (Germanates)
E : Phyllosilicates
B : Double nets with 4- and 6-membered rings
72.5.1.1

72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
5 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with corrugated and complex layers
14.6.7

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

Physical Properties of Rhodesite

Silky
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
White
Hardness (Mohs):
3 - 4
Cleavage:
Distinct/Good
Good on {100}
Density:
2.27 - 2.36 g/cm3 (Measured)    2.26 g/cm3 (Calculated)

Optical Data of Rhodesite

Type:
Biaxial (+)
RI values:
nα = 1.501 - 1.504 nβ = 1.506 - 1.508 nγ = 1.513 - 1.518
2V:
Calculated: 68.1°
Max Birefringence:
δ = 0.012 - 0.014
Image 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 Rhodesite

IMA Formula:
K2Ca2Si8O19 · 5H2O
Elements listed in formula:
Common Impurities:
Al,Fe,Mg,Na

Crystallography of Rhodesite

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 23.42 Å, b = 6.55 Å, c = 7.01 Å
Ratio:
a:b:c = 3.576 : 1 : 1.07
Unit Cell Volume:
V 1,075.34 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Matted silky fibers, flattened rosettes, irregular segregations, crusts.

Occurrences of Rhodesite

Type Occurrence of Rhodesite

Relationship of Rhodesite to other Species

9.EB.05MacdonalditeBaCa4Si16O36(OH)2 · 10H2O
9.EB.10DelhayeliteK7Na3Ca5Al2Si14O38F4Cl2
9.EB.10HydrodelhayeliteKCa2(Si7Al)O17(OH)2 · 6H2O
9.EB.15Monteregianite-(Y)KNa2YSi8O19 · 5H2O
9.EB.20CarletoniteKNa4Ca4Si8O18(CO3)4(F,OH) · H2O
14.6.1CombeiteNa2Ca2Si3O9
14.6.2PectoliteNaCa2Si3O8(OH)
14.6.3Pectolite-M2abcNaCa2[HSi3O9]
14.6.4DenisoviteKCa2Si3O8F
14.6.5TokkoiteK2Ca4Si7O18(OH)F
14.6.6MountainiteKNa2Ca2[Si8O19(OH)] · 6H2O
14.6.8MiseriteKCa6Si8O22(OH)
14.6.9ÅkermaniteCa2MgSi2O7
14.6.10MonticelliteCaMgSiO4
14.6.11MerwiniteCa3Mg(SiO4)2
14.6.12DiopsideCaMgSi2O6
14.6.13Tremolite◻Ca2Mg5Si8O22(OH)2

Other Names for Rhodesite

Name in Other Languages:
German:Rhodesit
Russian:Родзит
Spanish:Rhodesita

Other Information

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

References for Rhodesite

Reference List:
Mountain, E.D. (1957) Rhodesite, a new mineral from the Bultfontein mine, Kimberley. Mineralogical Magazine: 31: 607-610.

Gard, J.A., Taylor, H.F.W., Chalmers, R.A. (1957) An investigation of two new minerals: rhodesite and mountainite. Mineralogical Magazine: 31: 611-623.

Hesse, K.F., Liebau, F., Merlino, S. (1992) Crystal structure of rhodesite, HK1-xNax+2y Ca2-y(lB,3,22∞)[Si8O19]·(6-z)H2O, from three localities and its relation to other silicates with dreier double layers. Zeitschrift für Kristallographie: 199: 25-48.

Internet Links for Rhodesite

mindat.org URL:
https://www.mindat.org/min-3403.html
Please feel free to link to this page.

Localities for Rhodesite

This 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 for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
Austria
 
  • Styria
    • Bad Gleichenberg
      • Wilhelmsdorf
Postl, W. (1997); R. Exel: Die Mineralien und Erzlagerstätten Österreichs (1993)
    • Bad Radkersburg
      • Klöch
Taucher, J. et al. (1989)
    • Feldbach
      • Mühldorf
Postl, W. (1987); Exel, R. (1993)
Germany
 
  • Bavaria
    • Franconia
      • Maroldsweisach
Hesse K F, Liebau F, Merlino S (1992) Crystal structure of rhodesite, HK1-xNax+2y Ca2-y(lB,3,22∞)[Si8O19]·(6-z)H2O, from three localities and its relation to other silicates with dreier double layers. Zeitschrift für Kristallographie 199, 25-48; Wittern: "Mineralfundorte in Deutschland", 2001
  • Hesse
    • Vogelsberg
      • Ortenberg
  • Rhineland-Palatinate
    • Eifel
      • Mayen
        • Ettringen
          • Bellerberg volcano
[Blass, G., Graf, H.W., Neue Mineralfunde - mineralogische Raritäten - aus der Vulkaneifel, Mineralien-Welt 7/5, 28, 1996] [A. Wittern: Mineralfundorte in Deutschland, Schweizerbart (Stuttgart), 2001]
Italy
 
  • Umbria
    • Terni Province
      • San Venanzo
Stoppa, F., Sharygin, V.V., and Cundari, A. (1997): Mineralogy and Petrology 61, 27-45.; Sharygin, V. V., Pekov, I. V., Zubkova, N. V., Khomyakov, A. P., Stoppa, F., & Pushcharovsky, D. Y. (2013). Umbrianite, K7Na2Ca2 [Al3Si10O29] F2Cl2, a new mineral species from melilitolite of the Pian di Celle volcano, Umbria, Italy. European Journal of Mineralogy, 25(4), 655-669.
South Africa (TL)
 
  • Northern Cape Province
    • Francis Baard District
      • Kimberley
Mountain E D (1957) Rhodesite, a new mineral from the Bultfontein mine, Kimberley. Mineralogical Magazine 31, 607-610; Minerals of South Africa
USA
 
  • California
    • Trinity Co.
      • Klamath Mts
        • Trinity Mts
          • Halls Gulch District
            • Wildcat Peak
Sheppard, R.A. and Gude, A.J. (1969a) Rhodesite from Trinity County, California. American Mineralogist: 54: 251-255; 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: 441, 442; www.mineralsocal.org.
Mineral and/or Locality  
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