Hohmannite Mineral Data

General Hohmannite Information

Chemical Formula:

Fe+++2(SO4)2(OH)2•7(H2O)

Composition:

Molecular Weight = 463.94 gm

Iron 24.07 % Fe 34.42 % Fe₂O₃

Hydrogen 3.48 % H 31.06 % H₂O

Sulfur 13.82 % S 34.51 % SO₃

Oxygen 58.63 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe³⁺₂(SO₄)₂(OH)₂•7(H₂O)

Environment:

Low-temperature precipitate in oxidized iron sulfide deposits.

IMA Status:

Valid Species (Pre-IMA) 1888

Locality:

Antofagasta, from near Caracoles, Sierra Gorda district, Chile. Link to MinDat.org Location Data.

Name Origin:

Named for Thomas Hohmann (1843-1897), mining engineer of Valparaiso, Chile who discovered the first specimens.

Name Pronunciation:

Hohmannite + Pronunciation

Synonym:

Castanite

ICSD 37328

PDF 17-155

Hohmannite Image

Images:

Hohmannite Metahohmannite

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

Hohmannite Crystallography

Axial Ratios:

a:b:c =0.8318:1:0.659

Cell Dimensions:

a = 9.05, b = 10.88, c = 7.17, Z = 2; alpha = 90.15°, beta = 90.58°, gamma = 107° V = 675.10 Den(Calc)= 2.28

Crystal System:

Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 7.92(1), 8.69(0.8), 10.4(0.6),

Physical Properties of Hohmannite

Cleavage:

{???} Perfect, {???} Imperfect

Color:

Brown, Orange brown, Reddish brown.

Density:

2.2

Diaphaneity:

Transparent to Translucent

Hardness:

3 - Calcite

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

orange

Optical Properties of Hohmannite

Gladstone-Dale:

CI meas= -0.023 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.013 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2715,KPDmeas= 0.2814,KC= 0.2751
Ncalc = 1.61 - 1.63

Optical Data:

Biaxial (-), a=1.559, b=1.643, g=1.655, bire=0.0960

Calculated Properties of Hohmannite

Electron Density:

Bulk Density (Electron Density)=2.32 gm/cc
note: Specific Gravity of Hohmannite =2.28 gm/cc.

Fermion Index:

Fermion Index = 0.0064272507
Boson Index = 0.9935727493

Photoelectric:

PE_Hohmannite= 7.83 barns/electron
U=PE_Hohmannite x rElectron Density= 18.16 barns/cc.

Radioactivity:

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

Hohmannite Classification

Dana Class:

31.09.04.01 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.09)where (A+ B++) (XO4) Zqï¿½x(H2O)

(31.09.04)Dana Group

31.09.04.01 Hohmannite Fe2(SO4)2(OH)2•7(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 Hohmannite Information

References:

NAME( AntBidBlaNic5) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Hohmannite :
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
15 - WWW-MINCRYST

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

Hohmannite

Fe+++2(SO4)2(OH)2•7(H2O)
Dana No: 31.09.04.01 Strunz No: 07.DB.30
Locality:

Notes:

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