Koragoite Mineral Data

Koragoite Mineral Data +

General Koragoite Information

Chemical Formula:

(Mn++,Fe+++)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20

Composition:

Molecular Weight = 1,241.59 gm

Tantalum 16.03 % Ta 19.57 % Ta₂O₅

Titanium 1.16 % Ti 1.93 % TiO₂

Manganese 13.50 % Mn 12.86 % MnO / 5.09 % Mn₂O₃

Niobium 17.96 % Nb 25.69 % Nb₂O₅

Iron 3.37 % Fe 4.82 % Fe₂O₃

Tungsten 22.21 % W 28.01 % WO₃

Oxygen 25.77 % O

______ ______

100.00 % 97.97 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺_2.25Fe³⁺_0.75Nb_1.2Ta_0.6Ti_0.3Nb_1.2Mn³⁺_0.8W_1.5Ta_0.5O₂₀

Environment:

In granitic pegmatites.

IMA Status:

Approved IMA 1995

Locality:

Vez-Dara River valley, Shakhdara Range, in the southwestern Pamir Mountains, Tajikistan. Link to MinDat.org Location Data.

Name Origin:

Named after Aleksei Aleksandrovich Korago (1942–1993), geologist who investigated the formation of river pearls in the Arkhangel'sk district of Russia, and the origin of amber.

Synonym:

IMA1994-049

Koragoite Image

Images:

Koragoite

Comments: Black tabular crystals of koragoite in matrix.
Location: Vez-Dara River Valley, Shakhdara Range, Khorog Region, Gorno-Badakhshan District, Pamir Mts, Tajikistan. Scale: Picture size 1.8 mm.
© Thomas Witzke / Abraxas-Verlag

Koragoite Crystallography

Axial Ratios:

a:b:c =4.8912:1:1.1392

Cell Dimensions:

a = 24.73, b = 5.056, c = 5.76, Z = 2; beta = 103.5° V = 700.30 Den(Calc)= 5.89

Crystal System:

Monoclinic - SphenoidalH-M Symbol (2) Space Group: P 2₁

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

By Intensity(I/I_o): 2.98(1), 3.69(0.8), 3.74(0.8),

Physical Properties of Koragoite

Cleavage:

None

Color:

Red, Brownish red.

Density:

4.7 - 6.22, Average = 5.46

Diaphaniety:

Opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

4-5 - Fluorite-Apatite

Luster:

Metallic

Streak:

grayish brown

Optical Properties of Koragoite

RL Anisotrophism:

Weak.

RL Bireflectance:

Weak.

RL Color:

Light gray.

RL Pleochroism:

None.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Koragoite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
470 nm	19.20	18.00
546 nm	18.50	17.50
589 nm	19.30	18.50
650 nm	16.50	16.00

**Calculated Relative Intensity Colors of Koragoite in Air**
Relative Intensity	0%	60%	100%	120%	180%	240%	300%	360%	420%	480%	510%
R₁
R₂

Calculated Properties of Koragoite

Electron Density:

r_electron=5.24 gm/cc
note: r_Koragoite=5.89 gm/cc.

Fermion Index

Fermion Index = 0.03407
Boson Index = 0.96593

Photoelectric:

PE_Koragoite= 488.76 barns/electron
U=PE_Koragoite x r_electron=2,560.01 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Koragoite is Not Radioactive

Koragoite Classification

Dana Class:

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

(8.7)Dana Type

(8.7.12)Dana Group

8.7.12.1 Koragoite (Mn,Fe)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20 P 2₁ 2

Strunz Class:

IV/D.17-05 IV - Oxides

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

IV/D.17 - Qitianglinite - Lithiowodginite series

IV/D.17-05 Koragoite (Mn,Fe)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20 P 2₁ 2

IV/D.17-10 Qitianlingite Fe2Nb2WO10 P bcn 2/m 2/m 2/m

IV/D.17-20 Ashanite? (Nb,Ta,U,Fe,Mn)4O8 Pcan 2/m 2/m 2/m

IV/D.17-30 Ixiolite (Ta,Nb,Sn,Mn,Fe)O2 P 2/c 2/m

IV/D.17-40 Titanowodginite (Mn,Fe)(Ti,Sn)(Ta,Nb)2O8 C 2/c 2/m

IV/D.17-50 Wodginite Mn(Sn,Ta)(Ta,Nb)2O8 C 2/c 2/m

IV/D.17-55 Ferrotitanowodginite! FeTiTa2O8 C 2/m 2/m

IV/D.17-60 Ferrowodginite FeSnTa2O8 C 2/c 2/m

IV/D.17-70 Lithiowodginite LiTa3O8 C 2/c 2/m

Other Koragoite Information

References:

NAME( MinRec) PHYS. PROP.(Am.Min.,Vol.81,1996) OPTIC PROP.(MinRec, v 29, p 473)

See Also:

Links to other databases for Koragoite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -Handbook of Mineralogy (UofA) 6 -MinDAT 7 -MinMax(Deutsch) 8 -MinMax(English) 9 -Mineralienatlas (Deutsch) 10 -QUT Mineral Atlas 11 - WWW-MINCRYST

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Print or Cut-and-Paste your Koragoite Specimen Label here :

Koragoite

(Mn++,Fe+++)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20
Dana No: 8.7.12.1 Strunz No: IV/D.17-05
Locality:

Notes: