Metahohmannite Mineral Data

General Metahohmannite Information

Chemical Formula:

Fe+++2[O(SO4)2]•4(H2O)

Composition:

Molecular Weight = 391.88 gm

Iron 28.50 % Fe 40.75 % Fe₂O₃

Hydrogen 2.06 % H 18.39 % H₂O

Sulfur 16.37 % S 40.86 % SO₃

Oxygen 53.08 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe³⁺₂(O)(SO₄)₂•4(H₂O)

Environment:

Formed rapidly from the dehydration of hohmannite.

IMA Status:

Valid Species (Pre-IMA) 1938

Locality:

Chuquicamata, Quetena, and Alcaparrosa, Chile. Link to MinDat.org Location Data.

Name Origin:

Named after the similarity to hohmannite, with a lower state of hydration.

Name Pronunciation:

Metahohmannite + Pronunciation

Metahohmannite Image

Images:

Click Here for Larger Metahohmannite Image

Metahohmannite Hohmannite

Comments: Orange opaque prismatic microcrystals of hohmannite mixed with yellow metahohmanite.
Location: Chuquicamata, Antofagasta, Chile. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Metahohmannite

Comments: Orange-yellow earthy massive metahohmannite with orange hohmannite.
Location: Quetena, Antofagasta, Chile. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Metahohmannite Crystallography

Axial Ratios:

a:b:c =0.752:1:0.7319

Cell Dimensions:

a = 7.3484, b = 9.771, c = 7.1521, Z = 2; alpha = 91.684°, beta = 98.523°, gamma = 86.39° V = 506.63 Den(Calc)= 2.57

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 7.18(1), 2.49(0.7), 2.7(0.7),2.96(0.7), 3.28(0.7), 4.27(0.7), 7.04(0.6), 9.7(0.6),

Crystal Structure:

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drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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Scordari F , Ventruti G , Gualtieri A F , American Mineralogist , 89 (2004) p.265-370, The structure of metahohmannite, Fe2[O(SO4)2].4H2O,, by in situ synchrotron powder diffraction

Physical Properties of Metahohmannite

Color:

Orange.

Habit:

Pulverulent - Forms a loose, poorly-coherent powdery mass.

Streak:

light yellow

Optical Properties of Metahohmannite

Gladstone-Dale:

CI calc= -0.065 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2803,KC= 0.2632
Ncalc = 1.68

Optical Data:

Biaxial (+), a=1.709, b=1.718, g=1.734, bire=0.0250, 2V(Calc)=76, 2V(Meas)=70.

Pleochroism (x):

pale yellow.

Pleochroism (y):

reddish yellow.

Pleochroism (z):

reddish brown.

Calculated Properties of Metahohmannite

Electron Density:

Bulk Density (Electron Density)=2.57 gm/cc
note: Specific Gravity of Metahohmannite =2.57 gm/cc.

Fermion Index:

Fermion Index = 0.0075276504
Boson Index = 0.9924723496

Photoelectric:

PE_{Metahohmannite}= 9.35 barns/electron
U=PE_{Metahohmannite} x rElectron Density= 24.04 barns/cc.

Radioactivity:

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

Metahohmannite Classification

Dana Class:

31.09.05.01 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.09)where (A+ B++) (XO4) Zq·x(H2O)

(31.09.05)Dana Group

31.09.05.01 Metahohmannite Fe2[O(SO4)2]•4(H2O) P1 1

Strunz Class:

07.DB.30 07 - SULFATES (SELENATES, TELLURATES)

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

07.DB -With only medium-sized cations; insular octahedra and finite groups

07.DB.30 Amarantite Fe(SO4)(OH)•3(H2O) P1 1

07.DB.30 Hohmannite Fe2(SO4)2(OH)2•7(H2O) P1 1

07.DB.30 Metahohmannite Fe2[O(SO4)2]•4(H2O) P1 1

Other Metahohmannite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990, AmMin, v 89, p 265) OPTIC PROP.(Dana8)

See Also:

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

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

Metahohmannite

Fe+++2[O(SO4)2]•4(H2O)
Dana No: 31.09.05.01 Strunz No: 07.DB.30
Locality:

Notes: