Shigaite Mineral Data

General Shigaite Information

Chemical Formula:

Mn++7Al4(SO4)2(OH)22•8(H2O)

Composition:

Molecular Weight = 1,202.90 gm

Manganese 31.97 % Mn 41.28 % MnO

Aluminum 8.97 % Al 16.95 % Al₂O₃

Hydrogen 3.18 % H 28.46 % H₂O

Sulfur 5.33 % S 13.31 % SO₃

Oxygen 50.54 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₇Al₄(SO₄)₂(OH)₂₂•8(H₂O)

Environment:

Found in manganosite-rhodocrosite-sonolite ore.

IMA Status:

Approved IMA 1985

Locality:

Loi mine, Shinga Prefecture, Japan. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Name Pronunciation:

Shigaite

Synonym:

ICSD 82492

PDF 38-428

Shigaite Image

Images:

Shigaite Pyrochroite

Comments: Bronzy yellow crystals of shigaite set in a crystalline matrix of reddish black pychroite.
Location: N'Chwaning Mine, Kalahari Manganese Field, Northern Cape Province, South Africa. Scale: 2.8 x 2.3 cm.
© John Veevaert

Images:

Shigaite

Comments: Cluster of sharp, transparent crystals of brown shigaite to 1.2 cm across.
Location: N'Chwaning mine. South Africa. Scale: Aggregate size 1.2 cm.
© John Veevaert

Images:

Shigaite

Comments: Hexagonal aggregate of orange platy shigaite crystals on a jpale pink rhodocrosite matrix.
Location: N'Chwaning mine. South Africa. Scale: Crystal size 3 mm.
© Sandro Maggia/Minernet.it

Shigaite Crystallography

Axial Ratios:

a:c = 1:3.47708

Cell Dimensions:

a = 9.512, c = 33.074, Z = 3; V = 2,591.56 Den(Calc)= 2.31

Crystal System:

Trigonal - Rhombohedral H-M Symbol ( 3) Space Group: R 3

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

By Intensity(I/I_o): 10.98(1), 2.547(0.9), 5.47(0.9),

Physical Properties of Shigaite

Cleavage:

{0001} Perfect, {0001} Good

Color:

Light yellow, Orange.

Density:

2.32

Diaphaneity:

Transparent to Translucent

Fracture:

Flexible - Flexible fragments.

Habit:

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

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

2 - Gypsum

Luminescence:

Non-fluorescent.

Streak:

yellow white

Optical Properties of Shigaite

Dichroism (e):

very light yellow.

Dichroism (w):

light yellow.

Gladstone-Dale:

CI meas= 0.006 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.002 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2364,KPDmeas= 0.2353,KC= 0.2367
Ncalc = 1.55

Optical Data:

Uniaxial (-), w=1.546.

Calculated Properties of Shigaite

Electron Density:

Bulk Density (Electron Density)=2.31 gm/cc
note: Specific Gravity of Shigaite =2.31 gm/cc.

Fermion Index:

Fermion Index = 0.0006472376
Boson Index = 0.9993527624

Photoelectric:

PE_Shigaite= 8.58 barns/electron
U=PE_Shigaite x rElectron Density= 19.81 barns/cc.

Radioactivity:

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

Shigaite Classification

Dana Class:

31.01.02.01 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.01)where (A+ B++)m (XO4)p Zq�x(H2O), where m:p>6:1

(31.01.02)Dana Group

31.01.02.01 Shigaite Mn7Al4(SO4)2(OH)22•8(H2O) R 3 3

31.01.02.02 Nikischerite! NaFe6Al3(SO4)2(OH)18(H2O)12 R 3 3

Strunz Class:

07.DD.35 07 - SULFATES (SELENATES, TELLURATES)

07.D - Sulfates (selenates, etc.) with additional anions, with H2O

07.DD -With only medium-sized cations; sheets of edge-sharing octahedra

07.DD.35 Carrboydite (Ni,Cu)14Al9(SO4,CO3)6(OH)43•7(H2O) Unk Hex

07.DD.35 Glaucocerinite (Zn,Cu)5Al3(SO4)1.5(OH)16•9(H2O) Unk (HEX-R) Trig

07.DD.35 Honessite Ni6Fe2(SO4)(OH)16•4(H2O) R 3m 3 2/m

07.DD.35 Hydrowoodwardite! Cu1-xAlx(OH)2(SO4)x/2•n(H2O)with0<x<0.67andn>3x/2 R 3m 3 2/m

07.DD.35 Zincowoodwardite! [Zn1-xAlx(OH)2][(SO4)x/2(H2O)n] P 3- or R 3m 3

07.DD.35 Hydrohonessite Ni6Fe2(SO4)(OH)16•7(H2O) Unk Hex

07.DD.35 Motukoreaite Na2Mg38Al24(CO3)13(SO4)8(OH)108•56(H2O) R 3m 3 2/m

07.DD.35 Mountkeithite (Mg,Ni)11(Fe,Cr)3(SO4,CO3)3.5(OH)24•11(H2O) Unk Hex

07.DD.35 Shigaite Mn7Al4(SO4)2(OH)22•8(H2O) R 3 3

07.DD.35 Natroglaucocerinite! (Na,Zn,Cu)10Al6(SO4)3(OH)32•18(H2O)? Unk

07.DD.35 Wermlandite (Ca,Mg)Mg7(Al,Fe)2(SO4)2(OH)18•12(H2O) P 3c1 3 2/m

07.DD.35 Nikischerite! NaFe6Al3(SO4)2(OH)18(H2O)12 R 3 3

07.DD.35 Zincaluminite Zn6Al6(SO4)2(OH)26•5(H2O) Unk Hex

07.DD.35 Woodwardite Cu4Al2(SO4)(OH)12•2-4(H2O) Unk Hex

07.DD.35 Zincowoodwardite-3R! [Zn1BxAlx(OH)2][(SO4)x/2•n(H2O)],0.32<x<0.50,n=0.59 R 3m 3 2/m

07.DD.35 Zincowoodwardite-1T! [Zn1BxAlx(OH)2][(SO4)x/2•n(H2O)],x=0.33,n.0.96 P 3 3

Other Shigaite Information

References:

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

See Also:

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

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

Shigaite

Mn++7Al4(SO4)2(OH)22•8(H2O)
Dana No: 31.01.02.01 Strunz No: 07.DD.35
Locality:

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