Congolite Mineral Data

General Congolite Information

Chemical Formula:

(Fe++,Mg,Mn)3B7O13Cl

Composition:

Molecular Weight = 458.00 gm

Magnesium 4.78 % Mg 7.92 % MgO

Manganese 3.60 % Mn 4.65 % MnO

Iron 21.95 % Fe 28.24 % FeO

Boron 16.52 % B 53.20 % B₂O₃

Chlorine 7.74 % Cl 7.74 % Cl

- % Cl -1.75 % -O=Cl₂

Oxygen 45.41 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe²⁺_1.8Mg_0.9Mn²⁺_0.3B₇O₁₃Cl

Environment:

Found in insoluble residue from a drill core into sedimentary evaporites.

IMA Status:

Approved IMA 1972

Locality:

Brazzaville, Congo. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

ICSD 60504

PDF 25-2

Congolite Image

Images:

Congolite

Comments: Pearly crystalline grains of congolite.
Location: Brazzaville, Pool, Congo. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Congolite Crystallography

Axial Ratios:

a:c = 1:2.44175

Cell Dimensions:

a = 8.6225, c = 21.054, Z = 6; V = 1,355.60 Den(Calc)= 3.37

Crystal System:

Trigonal - Ditrigonal Pyramidal H-M Symbol (3m) Space Group: R 3c

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

By Intensity(I/I_o): 2.725(1), 3.05(0.8), 2.061(0.75),

Physical Properties of Congolite

Color:

Light red.

Density:

3.58

Diaphaneity:

Transparent

Hardness:

6.5-7.5

Luster:

Vitreous (Glassy)

Optical Properties of Congolite

Gladstone-Dale:

CI meas= 0.043 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.016 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2205,KPDmeas= 0.2075,KC= 0.2169
Ncalc = 1.73 - 1.78

Optical Data:

Uniaxial (-), e=1.731, w=1.755, bire=0.0240.

Calculated Properties of Congolite

Electron Density:

Bulk Density (Electron Density)=3.25 gm/cc
note: Specific Gravity of Congolite =3.37 gm/cc.

Fermion Index:

Fermion Index = 0.04
Boson Index = 0.96

Photoelectric:

PE_Congolite= 8.32 barns/electron
U=PE_Congolite x rElectron Density= 27.06 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Congolite is Not Radioactive

Congolite Classification

Dana Class:

25.06.02.01 (25)Anhydrous Borates Containing Hydroxyl or Halogen

(25.06)Dana Type

(25.06.02)Boracite Group (Trigonal: R3c)

25.06.02.01 Congolite (Fe,Mg,Mn)3B7O13Cl R 3c 3m

25.06.02.02 Trembathite (Mg,Fe)3B7O13Cl R 3c 3m

Strunz Class:

06.GA.10 06 - BORATES

06.G - Heptaborates and other Megaborates

06.GA -Tekto-heptaborates

06.GA.10 Congolite (Fe,Mg,Mn)3B7O13Cl R 3c 3m

06.GA.10 Trembathite (Mg,Fe)3B7O13Cl R 3c 3m

Other Congolite Information

References:

NAME( AntBidBlaNic5) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Congolite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Congolite

(Fe++,Mg,Mn)3B7O13Cl
Dana No: 25.06.02.01 Strunz No: 06.GA.10
Locality:

Notes:

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