Turtmannite Mineral Data

Turtmannite Mineral Data

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General Turtmannite Information

Chemical Formula:

(Mn,Mg)25.5[(V,As)O4]3(SiO4)3[AsO3]xO5-5x(OH)20+x

Composition:

Molecular Weight = 2,396.92 gm

Magnesium 2.54 % Mg 4.20 % MgO

Manganese 52.72 % Mn 68.07 % MnO

Vanadium 4.78 % V 8.54 % V₂O₅

Silicon 3.52 % Si 7.52 % SiO₂

Arsenic 3.28 % As 1.24 % As₂O₃ / 3.60 % As₂O₅

Hydrogen 0.84 % H 7.53 % H₂O

Oxygen 32.33 % O

______ ______

100.00 % 100.69 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₂₃Mg_2.5(VO₄)_2.25(AsO₄)_0.75(SiO₄)₃(AsO₃)_0.3O_3.5(OH)_20.03

Environment:

Manganoan paleokarst lenses in Triassic marbles metamorphosed to upper greenshist facies. Similar to mcgovernite; structure

IMA Status:

Approved IMA 2000 (Dana # Added)

Locality:

Barrhorn Unit (Central Alps) in the Triassic marbles near Turtmanntal, Valais, Switzerland. Link to MinDat.org Location Data.

Name Origin:

Named after the locality.

Turtmannite Image

Images:

Turtmannite

Comments: Orange-brownish grains of turtmannite in matrix.
Location: Pipji Glacier, Turtmanntal (Turtmann Valley), Wallis (Valais), Switzerland. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

Turtmannite Crystallography

Axial Ratios:

a:c = 1:2.47003

Cell Dimensions:

a = 8.259, c = 20.4, Z = 1; V = 1,205.08 Den(Calc)= 3.30

Crystal System:

Trigonal - Hexagonal ScalenohedralH-M Symbol (3 2/m) Space Group: R 3c

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

By Intensity(I/I_o): 2.86(1), 1.559(0.9), 3.26(0.8),4.13(0.7), 2.38(0.6), 3.46(0.6), 2.35(0.5),

Crystal Structure:

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Brugger J , Armbruster T , Meisser N , Hejny C , Grobety B , American Mineralogist , 86 (2001) p.1494-1505, Description and crystal structure of turtmannite, a new mineral with a, 68 Angstrom period related to mcgovernite, Note: z-coordinate of Mn12 has been modified

Physical Properties of Turtmannite

Cleavage:

[0001] Perfect

Color:

Bright yellow, Orange.

Density:

3.6 - 4, Average = 3.8

Diaphaniety:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Anhedral Grains - Granular minerals without the expression of crystal shapes

Habit:

Micaceous - Platy texture with "flexible" plates.

Habit:

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

Luster:

Vitreous (Glassy)

Streak:

colorless

Optical Properties of Turtmannite

Gladstone-Dale:

CI meas= 0.053 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.091 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2385,KPDmeas= 0.2071,KC= 0.2186

Optical Data:

Uniaxial (-), e=1.787.

Calculated Properties of Turtmannite

Electron Density:

r_electron=3.62 gm/cc
note: r_Turtmannite=3.80 gm/cc.

Fermion Index

Fermion Index = 0.00445
Boson Index = 0.99555

Photoelectric:

PE_Turtmannite= 17.04 barns/electron
U=PE_Turtmannite x r_electron= 61.62 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Turtmannite is Not Radioactive

Turtmannite Classification

Dana Class:

43.4.9.2 (43)Compound Phosphates, etc.

(43.4)(Anhydrous Compound Anions With Hydroxyl or Halogen)

(43.4.9)Dana Group

43.4.9.1 Mcgovernite Mn9Mg4Zn2As2Si2O17(OH)14 R 3c 3 2/m

43.4.9.2 Turtmannite ! (Mn,Mg)25.5[(V,As)O4]3(SiO4)3[AsO3]xO5-5x(OH)20x R 3c 3 2/m

Strunz Class:

VIII/B.11-15 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cations of octahedral and tetrahedral orientation [4/6]

VIII/B.11 - Dixenite - Kraisslite series

VIII/B.11-10 Dixenite CuMn14Fe(AsO3)5(SiO4)2(AsO4)(OH)6 R 3 3

VIII/B.11-15 Turtmannite (Mn,Mg)25.5[(V,As)O4]3(SiO4)3[AsO3]xO5-5x(OH)20x R 3c 3 2/m

VIII/B.11-20 Mcgovernite Mn9Mg4Zn2As2Si2O17(OH)14 R 3c 3 2/m

VIII/B.11-30 Kraisslite (Mn,Mg)24Zn3Fe(AsO3)2(AsO4)3(SiO4)6(OH)18 P 6₃22 6 2 2

VIII/B.11-40 Asbecasite Ca3(Ti,Sn)As6Si2Be2O20 P 3c 3m

Other Turtmannite Information

References:

NAME( AmMin, Vol 86, p 1494-1505) PHYS. PROP.(AmMin, Vol 86, p 1494-1505) OPTIC PROP.(AmMin, Vol 86, p 1494-1505)

See Also:

Links to other databases for Turtmannite :
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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Print or Cut-and-Paste your Turtmannite Specimen Label here :

Turtmannite

(Mn,Mg)25.5[(V,As)O4]3(SiO4)3[AsO3]xO5-5x(OH)20+x
Dana No: 43.4.9.2 Strunz No: VIII/B.11-15
Locality:

Notes: