Rhodesite Mineral Data

General Rhodesite Information

Chemical Formula:

KHCa2Si8O19•5(H2O)

Composition:

Molecular Weight = 732.57 gm

Potassium 3.20 % K 3.86 % K₂O

Sodium 1.26 % Na 1.69 % Na₂O

Calcium 10.94 % Ca 15.31 % CaO

Silicon 30.67 % Si 65.62 % SiO₂

Hydrogen 1.51 % H 13.53 % H₂O

Oxygen 52.42 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

K_0.6Na_0.4HCa₂Si₈O₁₉•5(H₂O)

Environment:

In a kimberlite pipe and also in altered silicic lavas.

IMA Status:

Valid Species (Pre-IMA) 1957

Locality:

Bultfontein diamond mine, Kimberley, Cape Province, South Africa. Link to MinDat.org Location Data.

Name Origin:

Named for Cecil John Rhodes (1853-1902), British founder of the DeBeers Mining Company and for Rhodes University, Grahamstown, South Africa where the mineral was studied.

Name Pronunciation:

Rhodesite + Pronunciation

Synonym:

ICSD 36551

PDF 22-1253

Rhodesite Image

Images:

Rhodesite Magadiite

Comments: Earth pale tan massive magadiite with dark yellow crystalline rhodesite.
Location: East Fork, Trinity River, Trinity County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Rhodesite

Comments: Pearly white to tan rhodesite crusts.
Location: Quarter-mile east of Trinity River, Trinity County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Rhodesite Crystallography

Axial Ratios:

a:b:c =3.5722:1:1.0755

Cell Dimensions:

a = 23.416, b = 6.555, c = 7.05, Z = 2; V = 1,082.12 Den(Calc)= 2.25

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pmam

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

By Intensity(I/I_o): 6.55(1), 4.39(0.45), 5.9(0.35),

Crystal Structure:

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Hesse K F , Liebau F , Merlino S , Zeitschrift fur Kristallographie , 199 (1992) p.25-48, Crystal structure of rhodesite, HK1-xNax+2yCa2-y{lB,3,2}[Si8O19]*(6-z)H2O,, from three localities and its relation to other silicates with dreier double layers, Locality: Zeilberg, Germany

View Additional jPOWD Structure files for Rhodesite
[1] [2]

Physical Properties of Rhodesite

Cleavage:

{100} Good

Color:

Silky white.

Density:

2.36

Diaphaneity:

Translucent to transparent

Habit:

Fibrous - Crystals made up of fibers.

Hardness:

3-4 - Calcite-Fluorite

Luster:

Silky

Streak:

white

Optical Properties of Rhodesite

Gladstone-Dale:

CI meas= 0.044 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.002 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2259,KPDmeas= 0.2154,KC= 0.2254
Ncalc = 1.51 - 1.53

Optical Data:

Biaxial (+), a=1.501-1.504, b=1.506-1.508, g=1.513-1.518, bire=0.0120-0.0140

Calculated Properties of Rhodesite

Electron Density:

Bulk Density (Electron Density)=2.28 gm/cc
note: Specific Gravity of Rhodesite =2.25 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Rhodesite= 2.87 barns/electron
U=PE_Rhodesite x r_electron= 6.53 barns/cc.

Radioactivity:

GRapi = 46.76 (Gamma Ray American Petroleum Institute Units)
Concentration of Rhodesite per GRapi unit = 2.14 (%)

Estimated Radioactivity from Rhodesite - barely detectable

Rhodesite Classification

Dana Class:

72.05.01.01 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.05)with corrugated and complex layers

(72.05.01)Rhodesite group

72.05.01.01 Rhodesite KHCa2Si8O19•5(H2O) Pmam 2/m 2/m 2/m

72.05.01.02 Monteregianite-(Y) (Na,K)6(Y,Ca)2Si16O38•10(H2O) P 2₁/m 2/m

72.05.01.03 Macdonaldite BaCa4[Si16O36(OH)2]•10(H2O) C mcm 2/m 2/m 2/m

72.05.01.04 Delhayelite (Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3•18(H2O) Pnmm 2/m 2/m 2/m

72.05.01.05 Hydrodelhayelite KCa2AlSi7O17(OH)2•6(H2O) Pnm21 mm2

72.05.01.06 Seidite-(Ce)! Na4(Ce,Sr)2{Ti(OH)2(Si8O18)}(O,OH,F)4•5(H2O) C/2c 2/m

Strunz Class:

09.EB.05 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.EB -Double nets with 4- and 6-membered rings

09.EB.05 Macdonaldite BaCa4[Si16O36(OH)2]•10(H2O) C mcm 2/m 2/m 2/m

09.EB.05 Rhodesite KHCa2Si8O19•5(H2O) Pmam 2/m 2/m 2/m

Other Rhodesite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

See Also:

Links to other databases for Rhodesite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Ask about Rhodesite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Rhodesite Specimen Label here :

Rhodesite

KHCa2Si8O19•5(H2O)
Dana No: 72.05.01.01 Strunz No: 09.EB.05
Locality:

Notes: