Rhodesite Mineral Data

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 65.61 % 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.

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

Diaphaniety:

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

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:

r_electron=2.28 gm/cc
note: r_Rhodesite=2.25 gm/cc.

Fermion Index

Fermion Index = 0.01472
Boson Index = 0.98528

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)

Estimated Radioactivity from Rhodesite - barely detectable

Rhodesite Classification

Dana Class:

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

(72.5)with corrugated and complex layers

(72.5.1)Rhodesite group

72.5.1.1 Rhodesite KHCa2Si8O19·5(H2O) Pmam 2/m 2/m 2/m

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

72.5.1.3 Macdonaldite BaCa4[Si16O36(OH)2]·10(H2O) C mcm 2/m 2/m 2/m

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

72.5.1.5 Hydrodelhayelite KCa2AlSi7O17(OH)2·6(H2O) Pnm21 mm2

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

Strunz Class:

VIII/H.38-20 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with tetrahedral-double layers and related structures

VIII/H.38 - Monteregianite-(Y) - Wickenburgite series

VIII/H.38-10 Monteregianite-(Y) (Na,K)6(Y,Ca)2Si16O38·10(H2O) P 2₁/m 2/m

VIII/H.38-20 Rhodesite KHCa2Si8O19·5(H2O) Pmam 2/m 2/m 2/m

VIII/H.38-30 Delhayelite (Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3·18(H2O) Pnmm 2/m 2/m 2/m

VIII/H.38-40 Hydrodelhayelite KCa2AlSi7O17(OH)2·6(H2O) Pnm21 mm2

VIII/H.38-50 Macdonaldite BaCa4[Si16O36(OH)2]·10(H2O) C mcm 2/m 2/m 2/m

VIII/H.38-60 Cymrite BaAl2Si2O8·(H2O) P 2₁ (pseudo-HEX) 2

VIII/H.38-65 Kampfite! Ba6[(Si,Al)O2]8(CO3)2Cl2(Cl,H2O)2 P 6₃mmc, P 6₂c, P 6₃mc, P 3₁ Hex

VIII/H.38-80 Lourenswalsite (K,Ba)2(Ti,Mg,Ca,Fe)4(Si,Al,Fe)6O14(OH)12 Unk (pseudo-HEX) Hex

VIII/H.38-90 Wickenburgite Pb3CaAl2Si10O27·4(H2O) P 3₁c 3m

Other Rhodesite Information

References:

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

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Rhodesite

KHCa2Si8O19·5(H2O)
Dana No: 72.5.1.1 Strunz No: VIII/H.38-20
Locality:

Notes: