Magnesiocolumbite Mineral Data

Magnesiocolumbite Mineral Data

General Magnesiocolumbite 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).

Synonym:

IMA2002-D

Magnocolumbite

Toddite

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Magnesiocolumbite 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),

Physical Properties of Magnesiocolumbite

Cleavage:

[010] Indistinct, [100] Indistinct

Color:

Brownish black, Black.

Density:

5.04

Diaphaniety:

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 Magnesiocolumbite

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

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 Magnesiocolumbite

Electron Density:

r_electron=5.01 gm/cc
note: r_{Magnesiocolumbite}=5.46 gm/cc.

Fermion Index

Fermion Index = 0.0094
Boson Index = 0.9906

Photoelectric:

PE_{Magnesiocolumbite}= 198.31 barns/electron
U=PE_{Magnesiocolumbite} x r_electron= 992.68 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Magnesiocolumbite is Not Radioactive

Magnesiocolumbite Classification

Dana Class:

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

(8.3)where A (B2O6)

(8.3.2)Dana Group

8.3.2.1 Ferrotantalite FeTa2O6 Pcan 2/m 2/m 2/m

8.3.2.2 Ferrocolumbite FeNb2O6 Pcan 2/m 2/m 2/m

8.3.2.3 Manganotantalite MnTa2O6 Pcan 2/m 2/m 2/m

8.3.2.4 Manganocolumbite (Mn,Fe)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

8.3.2.5 Magnesiocolumbite (Mg,Fe,Mn)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

8.3.2.6 Magnesiotantalite! (Mg,Fe)(Ta,Nb)2O6 P bcn 2/m 2/m 2/m

Strunz Class:

IV/D.18-10 IV - Oxides

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

IV/D.18 - Columbite series

IV/D.18-10 Magnesiocolumbite (Mg,Fe,Mn)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

IV/D.18-20 Manganocolumbite (Mn,Fe)(Nb,Ta)2O6 Pcan 2/m 2/m 2/m

IV/D.18-30 Ferrocolumbite FeNb2O6 Pcan 2/m 2/m 2/m

IV/D.18-35 Magnesiotantalite! (Mg,Fe)(Ta,Nb)2O6 P bcn 2/m 2/m 2/m

IV/D.18-40 Manganotantalite MnTa2O6 Pcan 2/m 2/m 2/m

IV/D.18-50 Ferrotantalite FeTa2O6 Pcan 2/m 2/m 2/m

Other Magnesiocolumbite Information

References:

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

See Also:

Links to other databases for Magnesiocolumbite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas

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Magnesiocolumbite

(Mg,Fe++,Mn)(Nb,Ta)2O6
Dana No: 8.3.2.5 Strunz No: IV/D.18-10
Locality:

Notes: