Columbite-(Mg) Mineral Data

General Columbite-(Mg) Information

Chemical Formula:

(Mg,Fe++,Mn)(Nb,Ta)2O6

Composition:

Molecular Weight = 330.49 gm

Magnesium 5.15 % Mg 8.54 % MgO

Tantalum 10.95 % Ta 13.37 % Ta₂O₅

Titanium 2.90 % Ti 4.83 % TiO₂

Manganese 1.66 % Mn 2.15 % MnO

Niobium 47.79 % Nb 68.36 % Nb₂O₅

Aluminum 0.82 % Al 1.54 % Al₂O₃

Iron 1.69 % Fe 2.17 % FeO

Oxygen 29.05 % O

______ ______

100.00 % 100.97 % = TOTAL OXIDE

Empirical Formula:

Mg_0.7Fe²⁺_0.1Mn²⁺_0.1Al_0.1Nb_1.7Ti_0.2Ta_0.2O₆

Environment:

In a pegmatite in partially assimilated dolomitic marbles.

IMA Status:

Approved IMA 1963

Locality:

Kukhi-Lal deposit, southwestern Pamir Mountains, Tadzhikistan. Link to MinDat.org Location Data.

Name Origin:

Named for the dominent MAGNESIum and its relationship to ferrocolumbite (formerly columbite).

Name Pronunciation:

Columbite-(Mg) + Pronunciation

Synonym:

IMA2002-D

Magnesiocolumbite - Renamed to Columbite-(Mg) by Mineralogical Record, v39 (2008), p 131

Magnocolumbite

Toddite

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Columbite-(Mg) Crystallography

Axial Ratios:

a:b:c =0.3542:1:0.3987

Cell Dimensions:

a = 5.02, b = 14.17, c = 5.65, Z = 4; V = 401.90 Den(Calc)= 5.46

Crystal System:

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

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

By Intensity(I/I_o): 2.955(1), 1.535(0.9), 1.723(0.9),

Crystal Structure:

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Pagola S , Carbonio R E , Alonso J A , Fernandez-Diaz M T , Journal of Solid State Chemistry , 134 (1997) p.76-84, Crystal structure refinement of Mg Nb2 O6 columbite from neutron powder, diffraction data and study of the ternary system MgO-Nb2O5-NbO, with evidence, of formation of new reduced pseudobrookite Mg5-xNb4+xO15-d (1.14

Physical Properties of Columbite-(Mg)

Cleavage:

{010} Indistinct, {100} Indistinct

Color:

Brownish black, Black.

Density:

5.04

Diaphaneity:

Opaque

Fracture:

Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

6.5 - Pyrite

Luminescence:

Non-fluorescent.

Luster:

Sub Metallic

Streak:

dark brown

Optical Properties of Columbite-(Mg)

Gladstone-Dale:

CI meas= -0.091 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2527,KPDmeas= 0.2738,KC= 0.251
Ncalc = 2.26 - 2.37

Optical Data:

Biaxial (-), a=2.33-2.36, g=2.39-2.44, bire=0.0600-0.0800

Pleochroism (x):

brownish yellow.

Pleochroism (z):

brownish red.

Calculated Properties of Columbite-(Mg)

Electron Density:

Bulk Density (Electron Density)=5.01 gm/cc
note: Specific Gravity of Columbite-(Mg) =5.46 gm/cc.

Fermion Index:

Fermion Index = 0.0094051723
Boson Index = 0.9905948277

Photoelectric:

PE_{Columbite-(Mg)}= 198.31 barns/electron
U=PE_{Columbite-(Mg)} x rElectron Density= 992.68 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Columbite-(Mg) is Not Radioactive

Columbite-(Mg) Classification

Dana Class:

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

(08.03)where A (B2O6)

(08.03.02)Tantalite - Columbite Series

08.03.02.01 Tantalite-(Fe) FeTa2O6 Pcan 2/m 2/m 2/m

08.03.02.02 Columbite-(Fe) FeNb2O6 Pcan 2/m 2/m 2/m

08.03.02.03 Tantalite-(Mn) MnTa2O6 Pcan 2/m 2/m 2/m

08.03.02.04 Columbite-(Mn) (Mn,Fe)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

08.03.02.05 Columbite-(Mg) (Mg,Fe,Mn)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

08.03.02.06 Tantalite-(Mg)! (Mg,Fe)(Ta,Nb)2O6 P bcn 2/m 2/m 2/m

Strunz Class:

04.DB.35 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

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

04.DB -With medium-sized cations; chains of edge-sharing octahedra

04.DB.35 Columbite-(Mg) (Mg,Fe,Mn)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

04.DB.35 Tantalite-(Fe) FeTa2O6 Pcan 2/m 2/m 2/m

04.DB.35 Columbite-(Fe) FeNb2O6 Pcan 2/m 2/m 2/m

04.DB.35 Columbite-(Mn) (Mn,Fe)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

04.DB.35 Qitianlingite Fe2Nb2WO10 P bcn 2/m 2/m 2/m

04.DB.35 Tantalite-(Mn) MnTa2O6 Pcan 2/m 2/m 2/m

04.DB.35 Tantalite-(Mg)! (Mg,Fe)(Ta,Nb)2O6 P bcn 2/m 2/m 2/m

Other Columbite-(Mg) Information

References:

NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic3)

See Also:

Links to other databases for Columbite-(Mg) :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Print or Cut-and-Paste your Columbite-(Mg) Specimen Label here :

Columbite-(Mg)

(Mg,Fe++,Mn)(Nb,Ta)2O6
Dana No: 08.03.02.05 Strunz No: 04.DB.35
Locality:

Notes: