Sturmanite Mineral Data

Sturmanite Mineral Data +

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General Sturmanite Information

Chemical Formula:

Ca6(Fe+++,Al,Mn++)2(SO4)2[B(OH)4](OH)12·25(H2O)

Composition:

Molecular Weight = 1,265.59 gm

Calcium 19.00 % Ca 26.59 % CaO

Manganese 1.30 % Mn 1.68 % MnO

Aluminum 1.28 % Al 2.42 % Al₂O₃

Iron 5.30 % Fe 7.57 % Fe₂O₃

Boron 0.85 % B 2.75 % B₂O₃

Hydrogen 5.26 % H 46.97 % H₂O

Sulfur 5.07 % S 12.65 % SO₃

Oxygen 61.95 % O

______ ______

100.00 % 100.63 % = TOTAL OXIDE

Empirical Formula:

Ca₆Fe³⁺_1.2Al_0.6Mn²⁺_0.3(SO₄)₂B(OH)₁₆·25(H₂O)

IMA Status:

Approved IMA 1983

Locality:

Black Rock mine, Kuruman district, Cape Province, South Africa. Link to MinDat.org Location Data.

Name Origin:

Named for B. Darko Sturman (1937-), Canadian mineralogist, Royal Ontario Museum, Toronto, Canada.

Synonym:

IMA1981-011

Sturmanite Image

Images:

Sturmanite

Comments: Sharply terminated dark yellowish crystal of sturmanite with a few lesser crystals attached to one side.
Location: N'Chwaning mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: 17 x 10 x 16 mm.
© Dan Weinrich

Sturmanite Crystallography

Axial Ratios:

a:c = 1:1.9525

Cell Dimensions:

a = 11.16, c = 21.79, Z = 2; V = 2,350.26 Den(Calc)= 1.79

Crystal System:

Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: P 3₁c

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

By Intensity(I/I_o): 9.67(1), 3.89(0.7), 5.58(0.7),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Pushcharovsky D Y , Lebedeva Y S , Zubkova N V , Pasero M , Bellezza M , Merlino S , Chukanov N V , The Canadian Mineralogist , 42 (2004) p.723-729, The crystal structure of sturmanite, Locality: Black Rock mine, Kuruman District, Kalahari manganese field, North Cape province, South Africa

Physical Properties of Sturmanite

Cleavage:

[1010] Perfect

Color:

Greenish yellow, Yellow, Yellow green, Orange brown.

Density:

1.847

Diaphaniety:

Transparent to Translucent

Habit:

Hexagonal - Six-sided crystal shape in cross-section or habit.

Habit:

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

Habit:

Pyramidal - Crystals are shaped like pyramids.

Hardness:

2.5 - Finger Nail

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

yellow white

Optical Properties of Sturmanite

Dichroism (e):

pale green.

Dichroism (w):

pale yellowish green.

Gladstone-Dale:

CI meas= 0.014 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.017 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2807,KPDmeas= 0.2721,KC= 0.276

Optical Data:

Uniaxial (+), w=1.5, e=1.505, bire=0.0050.

Calculated Properties of Sturmanite

Electron Density:

r_electron=1.93 gm/cc
note: r_Sturmanite=1.85 gm/cc.

Fermion Index

Fermion Index = 0.00376
Boson Index = 0.99624

Photoelectric:

PE_Sturmanite= 4.51 barns/electron
U=PE_Sturmanite x r_electron= 8.72 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Sturmanite is Not Radioactive

Sturmanite Classification

Dana Class:

32.4.4.2 (32)Compound Sulfates

(32.4)(hydrous) with poly-anionic formula

(32.4.4)Dana Group

32.4.4.1 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12·26(H2O) P 3₁c 3m

32.4.4.2 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12·25(H2O) P 3₁c 3m

32.4.4.3 Jouravskite Ca3Mn(SO4,CO3)2(OH)6·12(H2O) P 6₃/m 6/m

32.4.4.4 Thaumasite Ca3Si(CO3)(SO4)(OH)6·12(H2O) P 6₃/m 6/m

32.4.4.5 Carraraite! Ca3Ge(OH)6(SO4)(CO3)·12H2O P 6₃/m, or P 6₃ Hex

Strunz Class:

VI/D.13-50 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/D - Water-bearing sulfates with unfamiliar anions. cations of medium and very big size

VI/D.13 - Ettringite group, Ettringite - Sturmanite

VI/D.13-10 Ettringite Ca6Al2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

VI/D.13-20 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

VI/D.13-30 Jouravskite Ca3Mn(SO4,CO3)2(OH)6·12(H2O) P 6₃/m 6/m

VI/D.13-35 Carraraite! Ca3Ge(OH)6(SO4)(CO3)·12H2O P 6₃/m, or P 6₃ Hex

VI/D.13-40 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12·26(H2O) P 3₁c 3m

VI/D.13-50 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12·25(H2O) P 3₁c 3m

VI/D.13-60 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6·12(H2O) P 3₁c 3m

Other Sturmanite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

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Sturmanite

Ca6(Fe+++,Al,Mn++)2(SO4)2[B(OH)4](OH)12·25(H2O)
Dana No: 32.4.4.2 Strunz No: VI/D.13-50
Locality:

Notes: