Rankamaite Mineral Data

General Rankamaite Information

Chemical Formula:

(Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30

Composition:

Molecular Weight = 2,177.26 gm

Potassium 1.44 % K 1.73 % K₂O

Sodium 1.80 % Na 2.42 % Na₂O

Lithium 0.06 % Li 0.14 % Li₂O

Tantalum 57.34 % Ta 70.02 % Ta₂O₅

Niobium 12.80 % Nb 18.31 % Nb₂O₅

Aluminum 1.49 % Al 2.81 % Al₂O₃

Hydrogen 0.17 % H 1.53 % H₂O

Lead 2.85 % Pb 3.08 % PbO

Oxygen 22.05 % O

______ ______

100.00 % 100.04 % = TOTAL OXIDE

Empirical Formula:

Na_1.7K_0.8Pb_0.3Li_0.2Ta_6.9Nb₃Al_1.2O_26.3(OH)_3.7

Environment:

In alluvial concentrates. Probably derived from the alteration of simpsonite in a lithium pegmatite.

IMA Status:

Approved IMA 1969

Locality:

Mumba, Kivu, Zaire. Link to MinDat.org Location Data.

Name Origin:

Named for Kalervo Rankama (1913-), Finnish geochemist, University of Helsinki.

Name Pronunciation:

Rankamaite + Pronunciation

Rankamaite Image

Images:

Rankamaite

Comments: White, massive-fibrous rankamaite.
Location: Mumba, Kivu, Congo (ZaÃ¯re). Scale: Picture size 2 mm.
© Thomas Witzke / Abraxas-Verlag

Rankamaite Crystallography

Axial Ratios:

a:b:c =0.9711:1:0.2222

Cell Dimensions:

a = 17.19, b = 17.7, c = 3.933, Z = 2; V = 1,196.67 Den(Calc)= 6.04

Crystal System:

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

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

By Intensity(I/I_o): 2.97(1), 3.011(0.8), 3.375(0.6),

Physical Properties of Rankamaite

Cleavage:

None

Color:

White, Creamy white.

Density:

5.5

Diaphaneity:

Transparent

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

3-4 - Calcite-Fluorite

Luster:

Adamantine

Streak:

white

Optical Properties of Rankamaite

Gladstone-Dale:

CI meas= -0.122 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1821,KPDmeas= 0.2,KC= 0.1783
Ncalc = 1.98 - 2.08

Optical Data:

Biaxial (?), b=2.1

Calculated Properties of Rankamaite

Electron Density:

Bulk Density (Electron Density)=5.24 gm/cc
note: Specific Gravity of Rankamaite =6.04 gm/cc.

Fermion Index:

Fermion Index = 0.0065339073
Boson Index = 0.9934660927

Photoelectric:

PE_Rankamaite= 751.78 barns/electron
U=PE_Rankamaite x r_electron=3,942.07 barns/cc.

Radioactivity:

GRapi = 17.98 (Gamma Ray American Petroleum Institute Units)
Concentration of Rankamaite per GRapi unit = 5.56 (%)

Estimated Radioactivity from Rankamaite - barely detectable

Rankamaite Classification

Dana Class:

08.07.06.01 (08)Multiple Oxides with Nb, Ta, and Ti

(08.07)Dana Type

(08.07.06)Dana Group

08.07.06.01 Rankamaite (Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30 Pban 2/m 2/m 2/m

08.07.06.02 Sosedkoite (K,Na)5Al2(Ta,Nb)22O60 Pban 2/m 2/m 2/m

Strunz Class:

04.DM.05 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.D - Metal:Oxygen = 1:2 and similar

04.DM -With large (± medium-sized) cations; unclassified

04.DM.05 Rankamaite (Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30 Pban 2/m 2/m 2/m

04.DM.05 Sosedkoite (K,Na)5Al2(Ta,Nb)22O60 Pban 2/m 2/m 2/m

Other Rankamaite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Rankamaite :
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

Search for Rankamaite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Rankamaite :

A Bijoux Google Search for Rankamaite
Adam's Minerals Google Search for Rankamaite
Cape Minerals Google Search for Rankamaite
Dakota Matrix Minerals Google Search for Rankamaite
Excalibur Mineral Corp. Google Search for Rankamaite
Exceptional Minerals Google Search for Rankamaite
John Betts Fine Minerals Search for Rankamaite
McDougall Minerals Google Search for Rankamaite
Mineral News Website Link
Rock and Mineral Shows Google Search for Rankamaite
Weinrich Minerals, Inc. Google Search for Rankamaite

Ask about Rankamaite 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 Rankamaite Specimen Label here :

Rankamaite

(Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30
Dana No: 08.07.06.01 Strunz No: 04.DM.05
Locality:

Notes: