Rankamaite Mineral Data

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.

Rankamaite Image

Images:

Rankamaite

Comments: White, massive-fibrous rankamaite.
Location: Mumba, Kivu, Congo (Za?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

Diaphaniety:

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

Optical Data:

Biaxial (?), b=2.1

Calculated Properties of Rankamaite

Electron Density:

r_electron=5.24 gm/cc
note: r_Rankamaite=6.04 gm/cc.

Fermion Index

Fermion Index = 0.00653
Boson Index = 0.99347

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)

Estimated Radioactivity from Rankamaite - barely detectable

Rankamaite Classification

Dana Class:

8.7.6.1 (8)Multiple Oxides with Nb, Ta, and Ti

(8.7)Dana Type

(8.7.6)Dana Group

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

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

Strunz Class:

IV/D.27-40 IV - Oxides

IV/D - Oxides with metal : oxygen = 1:2 (MO2 and related compounds)

IV/D.27 - Bahianite - Sosedkoite series

IV/D.27-10 Bahianite Al5Sb3O14(OH)2 C 2/m 2/m

IV/D.27-20 Simpsonite Al4(Ta,Nb)3O13(OH) P 3 3

IV/D.27-30 Alumotantite AlTaO4 P bcn 2/m 2/m 2/m

IV/D.27-40 Rankamaite (Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30 Pban 2/m 2/m 2/m

IV/D.27-50 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 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 -École des Mines de Paris

Search for Rankamaite using:

[ALTAVISTA] [AOL] [About.com] [All-The-Web] [HotBot] [Ixquick] [LookSmart] [MAMMA] [MSN.COM] [Netscape] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Rankamaite :
AA Mineral Specimens
A-Rocks Auction
Adams Minerals
B and L Minerals
Dakota Matrix
Dan Weinrich Fine Minerals
Dan Weinrich Auctions
e-Rocks Auctions
Excalibur Minerals
Exceptional Minerals
Fabre Minerals
Greenside Minerals
John Betts Fine Minerals
Masons Minerals
Mineral News
Mineral of the Month Club
MineralsWeb Fine Minerals
Minernet.it
Rockshop.cz Kalat Fine Minerals
T G Fine Minerals
Wrights Rock Shop

Translate Rankamaite Mineral Data :

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: 8.7.6.1 Strunz No: IV/D.27-40
Locality:

Notes: