Woodallite Mineral Data

Woodallite Mineral Data

General Woodallite Information

Chemical Formula:

Mg6Cr2(OH)16Cl2·4(H2O)

Composition:

Molecular Weight = 659.31 gm

Magnesium 22.86 % Mg 37.90 % MgO

Aluminum 0.82 % Al 1.55 % Al₂O₃

Chromium 9.46 % Cr 13.83 % Cr₂O₃

Iron 4.24 % Fe 6.06 % Fe₂O₃

Hydrogen 3.67 % H 32.79 % H₂O

Carbon 0.36 % C 1.34 % CO₂

Chlorine 8.60 % Cl 8.60 % Cl

- % Cl -1.94 % -O=Cl₂

Oxygen 49.99 % O

______ ______

100.00 % 100.12 % = TOTAL OXIDE

Empirical Formula:

Mg_6.2Cr_1.2Fe³⁺_0.5Al_0.2(OH)₁₆Cl_1.6(CO₃)_0.2·4(H₂O)

Environment:

Altered dunite associated with Cr minerals.

IMA Status:

Approved IMA 2000 (Dana # Added)

Locality:

Mount Keith nickel deposit, 90 km NNE of Leinster, Western Australia. Link to MinDat.org Location Data.

Name Origin:

Named for Roy Woodall (1930-), Australian geologist.

Synonym:

IMA2000-042

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Woodallite Crystallography

Axial Ratios:

a:c = 1:7.77022

Cell Dimensions:

a = 3.103, c = 24.111, Z = 0.375; V = 201.05 Den(Calc)= 2.04

Crystal System:

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

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

By Intensity(I/I_o): 8.04(1)(003), 2.0072(0.6)(0.1.12), 4.0205(0.48)(006),2.624(0.3), 2.3488(0.05)(015),

Physical Properties of Woodallite

Cleavage:

[001] Perfect

Color:

Deep magenta, Purple.

Density:

2.062

Diaphaniety:

Transparent

Fracture:

Brittle - Sectile - Brittle fracture with slightly sectile shavings possible.

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

1.5-2 - Talc-Gypsum

Luster:

Resinous - Waxy

Streak:

pale pinkish white

Optical Properties of Woodallite

Gladstone-Dale:

CI meas= 0.055 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.045 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2672,KPDmeas= 0.2643,KC= 0.2797

Optical Data:

Uniaxial (-), e=1.535, w=1.555, bire=0.0200.

Calculated Properties of Woodallite

Electron Density:

r_electron=2.08 gm/cc
note: r_Woodallite=2.04 gm/cc.

Fermion Index

Fermion Index = 0.03302
Boson Index = 0.96698

Photoelectric:

PE_Woodallite= 4.40 barns/electron
U=PE_Woodallite x r_electron= 9.15 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Woodallite is Not Radioactive

Woodallite Classification

Dana Class:

6.4.5.2 (6)Hydroxides and Oxides Containing Hydroxyl

(6.4)containing multiple cations

(6.4.5)Dana Group

6.4.5.1 Iowaite Mg4Fe(OH)8OCl·2-4(H2O) R 3m 3 2/m

6.4.5.2 Woodallite ! Mg6Cr2(OH)16Cl2·4(H2O) R 3m 3 2/m

Strunz Class:

IV/F.05-15 IV - Oxides

IV/F - Hydroxides and oxidic hydrates, water-bearing oxides with layered structure

IV/F.05 - Meixnerite - Muskoxite series

IV/F.05-10 Meixnerite Mg6Al2(OH)18·4(H2O) R 3m 3 2/m

IV/F.05-15 Woodallite Mg6Cr2(OH)16Cl2·4(H2O) R 3m 3 2/m

IV/F.05-20 Iowaite Mg4Fe(OH)8OCl·2-4(H2O) R 3m 3 2/m

IV/F.05-30 Muskoxite Mg7Fe4O13·10(H2O) Unk (pseudo HEX-R) Trig

Other Woodallite Information

References:

NAME( AmMin, Vol 87, p 182) PHYS. PROP.(AmMin, Vol 87, p 182) OPTIC PROP.(AmMin, Vol 87, p 182)

See Also:

Links to other databases for Woodallite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - Crocoite.com Mineral Locations 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas

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

Woodallite

Mg6Cr2(OH)16Cl2·4(H2O)
Dana No: 6.4.5.2 Strunz No: IV/F.05-15
Locality:

Notes: