Gaudefroyite Mineral Data

Gaudefroyite Mineral Data +

General Gaudefroyite Information

Chemical Formula:

Ca4Mn+++3-x(BO3)3(CO3)(O,OH)3

Composition:

Molecular Weight = 582.85 gm

Calcium 27.51 % Ca 38.49 % CaO

Manganese 23.56 % Mn 33.86 % Mn₂O₃

Boron 5.56 % B 17.92 % B₂O₃

Hydrogen 0.13 % H 1.16 % H₂O

Carbon 2.06 % C 7.55 % CO₂

Oxygen 41.18 % O

______ ______

100.00 % 98.97 % = TOTAL OXIDE

Empirical Formula:

Ca₄Mn³⁺_2.5(BO₃)₃(CO₃)O_2.25(OH)_0.75

Environment:

An uncommon hydrothermal mineral in manganese deposits.

IMA Status:

Approved IMA 1964

Locality:

Tachgagalt, 17 km south-southwest of Ouarzazate, Anti-Atlas Mountains, Morocco. Link to MinDat.org Location Data.

Name Origin:

Named for Abbe Christophe Gaudefroy (1888-1971), French mineralogist who worked in Morocco.

Synonym:

ICSD 66846

PDF 17-154

Gaudefroyite Image

Images:

Gaudefroyite

Comments: Dark gray, prismatic gaudefroyite with crystals to 1.5 cm.
Location: N'Chwaning Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: 7.8 x 4.2 cm.
© John Veevaert

Gaudefroyite Crystallography

Axial Ratios:

a:c = 1:0.55633

Cell Dimensions:

a = 10.589, c = 5.891, Z = 2; V = 572.04 Den(Calc)= 3.38

Crystal System:

Hexagonal - PyramidalH-M Symbol (6) Space Group: P 6₃

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

By Intensity(I/I_o): 2.46(1), 2.62(1), 2.95(1),

Crystal Structure:

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Hoffmann C , Armbruster T , Kunz M , European Journal of Mineralogy , 9 (1997) p.7-19, Structure refinement of (001) disordered gaudefroyite Ca4Mn3[(BO3)3(CO3)O3]:, Jahn-Teller-distortion in edge-sharing chains of MnO6 octahedra

Physical Properties of Gaudefroyite

Cleavage:

None

Color:

Black.

Density:

3.35 - 3.5, Average = 3.42

Diaphaniety:

Subopaque

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

6 - Orthoclase

Luster:

Adamantine - Resinous

Streak:

brown

Optical Properties of Gaudefroyite

Dichroism (e):

pale yellowish brown.

Dichroism (w):

red orange.

Gladstone-Dale:

CI meas= -0.108 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.123 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2707,KPDmeas= 0.2672,KC= 0.2411

Optical Data:

Uniaxial (+), w=1.81, e=2.02, bire=0.2100.

RL Anisotrophism:

Strong in pale grays.

RL Color:

Gray with strong yellow-orange to reddish internal reflections.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Gaudefroyite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	11.20	15.40
420 nm	10.80	14.80
440 nm	10.40	14.20
460 nm	10.10	13.80
480 nm	9.90	13.40
500 nm	9.70	13.10
520 nm	9.60	12.80
540 nm	9.60	12.60
560 nm	9.50	12.30
580 nm	9.50	12.20
600 nm	9.40	12.10
620 nm	9.40	12.00
640 nm	9.30	11.90
660 nm	9.30	11.80
680 nm	9.30	11.70
700 nm	9.30	11.70

**Calculated Relative Intensity Colors of Gaudefroyite in Air**
Relative Intensity	0%	100%	200%	300%	400%	500%	600%	700%	800%	900%	920%
R₁
R₂

Calculated Properties of Gaudefroyite

Electron Density:

r_electron=3.34 gm/cc
note: r_Gaudefroyite=3.43 gm/cc.

Fermion Index

Fermion Index = 0.01186
Boson Index = 0.98814

Photoelectric:

PE_Gaudefroyite= 9.52 barns/electron
U=PE_Gaudefroyite x r_electron= 31.80 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Gaudefroyite is Not Radioactive

Gaudefroyite Classification

Dana Class:

27.1.2.1 (27)Compound Borates

(27.1)Dana Type

(27.1.2)Dana Group

27.1.2.1 Gaudefroyite Ca4Mn3-x(BO3)3(CO3)(O,OH)3 P 6₃ 6

Strunz Class:

V/G.04-100 V - Nitrates, Carbonates and Borates

V/G - "Insel" borates [BO3]3- "inseln"

V/G.04 - Ludwigite group

V/G.04-10 Ludwigite Mg2FeBO5 Pbam 2/m 2/m 2/m

V/G.04-20 Vonsenite Fe2FeBO5 Pbam 2/m 2/m 2/m

V/G.04-30 Azoproite (Mg,Fe)2(Fe,Ti,Mg)BO5 Pbam 2/m 2/m 2/m

V/G.04-40 Chestermanite Mg2(Fe,Mg,Al,Sb)BO3O2 Pbam 2/m 2/m 2/m

V/G.04-50 Fredrikssonite Mg2(Mn,Fe)O2(BO3) Pbam 2/m 2/m 2/m

V/G.04-60 Bonaccordite Ni2FeBO5 Pbam 2/m 2/m 2/m

V/G.04-70 Takeuchiite Mg2MnO2(BO3) Pnnm 2/m 2/m 2/m

V/G.04-80 Orthopinakiolite (Mg,Mn)2MnBO5 Pnnm 2/m 2/m 2/m

V/G.04-90 Blatterite (Mn,Mg)35Sb3(Mn,Fe)9(BO3)16O32 Pnnm 2/m 2/m 2/m

V/G.04-100 Gaudefroyite Ca4Mn3-x(BO3)3(CO3)(O,OH)3 P 6₃ 6

Other Gaudefroyite Information

References:

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

See Also:

Links to other databases for Gaudefroyite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - CalTech Mineral Spectroscopy 4 - EUROmin Project 5 -Google Images 6 -Google Scholar 7 -Handbook of Mineralogy (UofA) 8 -MinDAT 9 -MinMax(Deutsch) 10 -MinMax(English) 11 -Mineralienatlas (Deutsch) 12 -QUT Mineral Atlas 13 - WWW-MINCRYST 14 -École des Mines de Paris

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

Gaudefroyite

Ca4Mn+++3-x(BO3)3(CO3)(O,OH)3
Dana No: 27.1.2.1 Strunz No: V/G.04-100
Locality:

Notes: