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 % Ta2 O5
Titanium 2.90 % Ti 4.83 % TiO2
Manganese 1.66 % Mn 2.15 % MnO
Niobium 47.79 % Nb 68.36 % Nb2 O5
Aluminum 0.82 % Al 1.54 % Al2 O3
Iron 1.69 % Fe 2.17 % FeO
Oxygen 29.05 % O
______ ______
100.00 % 100.97 % = TOTAL OXIDE
Empirical Formula:
Mg0.7 Fe2+ 0.1 Mn2+ 0.1 Al0.1 Nb1.7 Ti0.2 Ta0.2 O6
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
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 - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pcan
X Ray Diffraction:
By Intensity(I/Io ): 2.955(1), 1.535(0.9), 1.723(0.9),
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:
PEColumbite-(Mg) = 198.31 barns/electronU=PEColumbite-(Mg) x r Electron 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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Columbite-(Mg)
(Mg,Fe++,Mn)(Nb,Ta)2O6
Dana No: 08.03.02.05 Strunz No: 04.DB.35
Locality:
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