Mineralogy Database

Koragoite Mineral Data

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General Koragoite Information

Help on Chemical  Formula: Chemical Formula: (Mn++,Fe+++)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20
Help on Composition: 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
Help on Empirical Formula: Empirical Formula: Mn2+2.25Fe3+0.75Nb1.2Ta0.6Ti0.3Nb1.2Mn3+0.8W1.5Ta0.5O20
Help on Environment: Environment: In granitic pegmatites.
Help on IMA Status: IMA Status: Approved IMA 1995
Help on Locality: Locality: Vez-Dara River valley, Shakhdara Range, in the southwestern Pamir Mountains, Tajikistan. Link to MinDat.org Location Data.
Help on Name Origin: 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.
Help on Name Pronunciation: Name Pronunciation: Koragoite + Pronunciation Say KORAGOITE
Help on Synonym: Synonym: IMA1994-049

Koragoite Image

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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

Help on Axial Ratios: Axial Ratios: a:b:c =4.8912:1:1.1392
Help on Cell Dimensions: Cell Dimensions: a = 24.73, b = 5.056, c = 5.76, Z = 2; beta = 103.5° V = 700.30 Den(Calc)= 5.89
Help on Crystal System: Crystal System: Monoclinic - Sphenoidal H-M Symbol (2) Space Group: P 21
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.98(1), 3.69(0.8), 3.74(0.8),

Physical Properties of Koragoite

Help on Cleavage: Cleavage: None
Help on Color: Color: Red, Brownish red.
Help on Density: Density: 4.7 - 6.22, Average = 5.46
Help on Diaphaneity: Diaphaneity: Opaque
Help on Fracture: Fracture: Brittle - Uneven - Very brittle fracture producing uneven fragments.
Help on Habit: Habit: Platy - Sheet forms (e.g. micas).
Help on Hardness: Hardness: 4-5 - Fluorite-Apatite
Help on Luster: Luster: Metallic
Help on Streak: Streak: grayish brown

Optical Properties of Koragoite

Help on Optical Data: Optical Data: NCalc= 2.24 - from Gladstone-Dale relationship (KC = 0.2097) where Ncalc=Dcalc*KC+1
NCalc= 2.15 - from Gladstone-Dale relationship (KC = 0.2097) where Ncalc=Dmeas*KC+1
Help on RL Anisotrophism: RL Anisotrophism: Weak.
Help on RL Bireflectance: RL Bireflectance: Weak.
Help on RL Color: RL Color: Light gray.
Help on RL Pleochroism: RL Pleochroism: None.
Help on Reflectivity 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
   0%   60% 100% 120% 180% 240% 300% 360% 420% 480% 510%

Calculated Properties of Koragoite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=5.24 gm/cc
note: Specific Gravity of Koragoite =5.89 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.03
Boson Index = 0.97
Help on Photoelectric: Photoelectric: PEKoragoite = 488.76 barns/electron
U=PEKoragoite x rElectron Density=2,560.01 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Koragoite is Not Radioactive

Koragoite Classification

Help on  Dana Class: Dana Class: (08)Multiple Oxides with Nb, Ta, and Ti
  (08.07)Dana Type
  (08.07.12)Dana Group Koragoite (Mn,Fe)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20 P 21 2
Help on  Strunz Class: Strunz Class: 04.DE.10 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate
  04.D - Metal:Oxygen = 1:2 and similar
  04.DE -With medium-sized cations; with various polyhedra
04.DE.10 Koragoite (Mn,Fe)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20 P 21 2

Other Koragoite Information

Help on References: References: NAME( MinRec) PHYS. PROP.(Am.Min.,Vol.81,1996) OPTIC PROP.(MinRec, v 29, p 473)
Help on See Also: See Also: Links to other databases for Koragoite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - Handbook of Mineralogy (UofA)
7 - MinDAT
8 - Mineralienatlas (Deutsch)
9 - Online Mineral Museum
10 - QUT Mineral Atlas
11 - Ruff.Info

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Dana No: Strunz No: 04.DE.10





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