Iowaite
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About Iowaite
Formula:
Mg6Fe3+2(OH)16Cl2 · 4H2O
Colour:
bluish green
Lustre:
Greasy
Hardness:
1½
Specific Gravity:
2.11
Crystal System:
Trigonal
Member of:
Name:
For the state of the type locality.
Type Locality:
Hydrotalcite Group. Chemically similar to kuliginite, which however is anhydrous.
Bluish green, becoming pale green with a rusty red tint on exposure to air (alteration to pyroaurite).
Bluish green, becoming pale green with a rusty red tint on exposure to air (alteration to pyroaurite).
Classification of Iowaite
Approved
First Published:
1967
4/F.05-20
4.FL.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
6.4.5.1
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
4 : Miscellaneous
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
4 : Miscellaneous
8.11.8
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
11 : Halides of Fe and Ni
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
11 : Halides of Fe and Ni
Physical Properties of Iowaite
Greasy
Transparency:
Translucent
Colour:
bluish green
Streak:
white
Hardness:
1½ on Mohs scale
Cleavage:
Perfect
Perfect basal cleavage
Perfect basal cleavage
Density:
2.11(2) g/cm3 (Measured)
Optical Data of Iowaite
Type:
Uniaxial (-)
RI values:
nω = 1.543 - 1.561 nε = 1.533 - 1.543
Max Birefringence:
δ = 0.010 - 0.018

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Low
Chemical Properties of Iowaite
Formula:
Mg6Fe3+2(OH)16Cl2 · 4H2O
Crystallography of Iowaite
Crystal System:
Trigonal
Class (H-M):
3m (3 2/m) - Hexagonal Scalenohedral
Space Group:
R3m
Cell Parameters:
a = 3.119(5) Å, c = 24.25(2) Å
Ratio:
a:c = 1 : 7.775
Unit Cell V:
204.30 ų (Calculated from Unit Cell)
Comment:
Call parameters from powder diffraction data
Occurrences of Iowaite
Paragenetic Mode(s):
• Serpentinization
Type Occurrence of Iowaite
General Appearance of Type Material:
Platy crystals 2-3mm in size
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 121706.
Geological Setting of Type Material:
Altered serpentinite in precambrian basement
Reference:
Kohls, D.W., Rodda,, J.L. (1967) Iowaite, a new hydrous magnesium hydroxide-ferric oxychloride from the Precambrian of Iowa. American Mineralogist: 52: 1261-1271.
Synonyms of Iowaite
Other Language Names for Iowaite
Varieties of Iowaite
Chromian Iowaite | Iowaite with significant replacement of Fe3+ by Cr3+ transitive to Woodallite. |
Relationship of Iowaite to other Species
Member of:
Other Members of this group:
Desautelsite | Mg6Mn3+2(OH)16[CO3] · 4H2O | Trig. 3m (3 2/m) |
Droninoite | Ni6Fe2+3(OH)16Cl2 · 4H2O | Trig. 3m (3 2/m) : R3m |
Hydrotalcite | Mg6Al2(OH)16[CO3] · 4H2O | Trig. 3m (3 2/m) : R3m |
Hydrotalcite-3R | Mg6Al2(CO3)(OH)16 · 4H2O | Trig. 3m (3 2/m) : R3m |
Meixnerite | Mg6Al2(OH)16(OH)2 · 4H2O | Trig. 3m (3 2/m) : R3m |
Pyroaurite | Mg6Fe3+2(OH)16[CO3] · 4H2O | Trig. 3m (3 2/m) : R3m |
Reevesite | Ni6Fe3+2(OH)16(CO3) · 4H2O | Trig. |
Stichtite | Mg6Cr3+2(OH)16[CO3] · 4H2O | Trig. 3m (3 2/m) : R3m |
Takovite | Ni6Al2(OH)16[CO3] · 4H2O | Trig. |
Woodallite | Mg6Cr2(OH)16Cl2 · 4H2O | Trig. |
Common Associates
Associated Minerals Based on Photo Data:
Magnetite | 8 photos of Iowaite associated with Magnetite on mindat.org. |
Valleriite | 7 photos of Iowaite associated with Valleriite on mindat.org. |
Calcite | 6 photos of Iowaite associated with Calcite on mindat.org. |
Fluorapatite | 4 photos of Iowaite associated with Fluorapatite on mindat.org. |
Lizardite | 2 photos of Iowaite associated with Lizardite on mindat.org. |
Gypsum | 1 photo of Iowaite associated with Gypsum on mindat.org. |
Brucite | 1 photo of Iowaite associated with Brucite on mindat.org. |
Pentlandite | 1 photo of Iowaite associated with Pentlandite on mindat.org. |
Woodallite | 1 photo of Iowaite associated with Woodallite on mindat.org. |
Muscovite | 1 photo of Iowaite associated with Muscovite on mindat.org. |
Related Minerals - Nickel-Strunz Grouping
4.FL. | Trébeurdenite | Fe2+2Fe3+4O2(OH)10CO3·3H2O | Trig. 3m (3 2/m) : R3m |
4.FL.05 | Woodallite | Mg6Cr2(OH)16Cl2 · 4H2O | Trig. |
4.FL.05 | Jamborite | Ni2+1-xCo3+x(OH)2-x(SO4)x · nH2O | Trig. 3m (3 2/m) : R3m |
4.FL.05 | Meixnerite | Mg6Al2(OH)16(OH)2 · 4H2O | Trig. 3m (3 2/m) : R3m |
4.FL.05 | Muskoxite | Mg7Fe4O13 · 10H2O | Trig. 3m (3 2/m) |
4.FL.05 | Fougèrite | Fe2+4Fe3+2(OH)12[CO3]·3H2O | Trig. 3m (3 2/m) : R3m |
4.FL.10 | Hydrocalumite | Ca4Al2(OH)12(Cl,CO3,OH)2 · 4H2O | Mon. 2 : P21 |
4.FL.15 | Kuzelite | Ca4Al2(OH)12[SO4] · 6H2O | Trig. |
4.FL.20 | Aurorite | (Mn2+,Ag,Ca)Mn4+3O7 · 3H2O | Trig. 3 : R3 |
4.FL.20 | Chalcophanite | (Zn,Fe,Mn)Mn3O7 · 3H2O | Trig. 3 : R3 |
4.FL.20 | Ernienickelite | NiMn3O7 · 3H2O | Trig. 3 : R3 |
4.FL.20 | Jianshuiite | (Mg,Mn,Ca)Mn3O7 · 3H2O | Trig. 3 : R3 |
4.FL.25 | Woodruffite | Zn2+x/2(Mn4+1-xMn3+x)O2·yH2O | Mon. 2/m : B2/m |
4.FL.30 | Asbolane | (Ni,Co)2-xMn4+(O,OH)4 · nH2O | Hex. |
4.FL.35 | Buserite | Na4Mn14O27 · 21H2O | |
4.FL.40 | Ranciéite | (Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O | Trig. 3 : P3 |
4.FL.40 | Takanelite | (Mn,Ca)Mn4O9 · H2O | Hex. |
4.FL.45 | Birnessite | (Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O | Mon. 2/m : B2/m |
4.FL.55 | Cianciulliite | Mn(Mg,Mn)2Zn2(OH)10 · 2-4H2O | Mon. 2/m : B2/m |
4.FL.60 | Jensenite | Cu3[TeO6] · 2H2O | Mon. 2/m : P21/m |
4.FL.65 | Leisingite | CuMg2Te6+O6 · 6H2O | Trig. 3 : P3 |
4.FL.70 | Akdalaite | 5Al2O3 · H2O | Hex. |
4.FL.75 | Cafetite | CaTi2O5 · H2O | Mon. 2/m : P21/b |
4.FL.80 | Mourite | UMo5O12(OH)10 | Mon. |
4.FL.85 | Deloryite | Cu4(UO2)(MoO4)2(OH)6 | Mon. |
Related Minerals - Hey's Chemical Index of Minerals Grouping
8.11.1 | Molysite | FeCl3 | Hex. |
8.11.2 | Hydromolysite | FeCl3 · 6H2O | |
8.11.3 | Rokühnite | FeCl2 · 2H2O | Mon. |
8.11.4 | Douglasite | K2[Fe2+Cl4(OH2)2] | Mon. |
8.11.5 | Erythrosiderite | K2[Fe3+Cl5(H2O)] | Orth. mmm (2/m 2/m 2/m) : Pnma |
8.11.6 | Rinneite | K3Na[FeCl6] | Trig. 3m (3 2/m) : R3c |
8.11.7 | Kremersite | (NH4,K)2[Fe3+Cl5(H2O)] | Orth. mmm (2/m 2/m 2/m) |
8.11.9 | Nickelbischofite | NiCl2 · 6H2O | Mon. |
8.11.10 | Lawrencite | (Fe2+,Ni)Cl2 | Trig. 3m (3 2/m) : R3m |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
References for Iowaite
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Kohls, D.W., Rodda,, J.L. (1967) Iowaite, a new hydrous magnesium hydroxide-ferric oxychloride from the Precambrian of Iowa. American Mineralogist: 52: 1261-1271.
Allmann, R., Donnay, J.D.H. (1969) About the structure of iowaite. American Mineralogist: 54: 296-299.
Braithwaite, R.S.W., Dunn, P.J., Pritchard, R.G., Paar, W.H. (1994) Iowaite, a re-investigation. Mineralogical Magazine: 58: 79-85.
Jambor, J.L., Roberts, A.C., Vanko, D.A. (1994) New mineral names. American Mineralogist: 79: 1009-1014.
Mills, S.J., Christy, A.G., Genin, J.-M.R., Kameda, T., Colombo, F. (2012) Nomenclature of the hydrotalcite supergroup: natural layered double hydroxides. Mineralogical Magazine: 76: 1289-1336.
Internet Links for Iowaite
mindat.org URL:
https://www.mindat.org/min-2038.html
Please feel free to link to this page.
Please feel free to link to this page.
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Localities for Iowaite
Locality List




All localities listed without proper references should be considered as questionable.
Australia | |
| Disseminated and Massive Nickel Sulphide Deposits,Honeymoon Well Complex, Western Australia; M Gole and M Woodhouse, Journal of the Virtual Explorer; ISSN 1441-8142 Vol 1 paper 2, 2000 |
Grguric, B.A., Seat, Z., Karpuzov, A.A., Simonov, O.N. (2013) The West Jordan deposit, a newly-discovered Type 2 dunite-hosted nickel sulphide system in the northern Agnew-Wiluna Belt, Western Australia. Ore Geology Reviews, Vol. 51, pg. 79-92 | |
| [AmMin 87:182] |
Canada | |
| HORVÁTH, L., PFENNINGER-HORVÁTH, E. and SPERTINI, F. (2013) The Jeffrey mine, Asbestos, Québec, Canada: A mineralogical review. Mineralogical Record, 44, 375-417. |
Pacific Ocean | |
| Dietrich Heling and Alexander Schwarz (1992) IOWAITE IN SERPENTINITE MUDS AT SITES 778, 779, 780, AND 784: A POSSIBLE CAUSE FOR THE LOW CHLORINITY OF PORE WATERS. Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 125 |
Poland | |
| Łukasz Kruszewski (2012) Unique chloride assemblage of exhalative origin from burning coal-mining dump in Radlin (Rybnik Coal Area, S Poland). Mineralogical Society of Poland Special Papers 40 |
| Koszowska E., Salata D. 2001: Minerals of the hydrotalcite group in metasomatically altered carbonate rocks from Zawiercie, S Poland. Mineralogia Polonica, vol. 32, no 1, 69-84 |
Russia | |
| Handbook of Mineralogy; Evseev, A. A. (1973) Siberia's Crystals and Symmetry in the Distribution of Occurences of Minerals. World of Stone 1:11-20 |
| Mazurov, M.P., Grishina, S.N., Istomin, V.E., and Titov, A.T. (2007): Geology of Ore Deposits 49(4), 271-284.; Mazurov et al (2007) Geology of Ore Deposits, 49, 271–284. |
| Pavel M. Kartashov data |
| Igor V. Pekov data |
South Africa | |
| Minerals of South Africa; Braithwaite, R. S. W., Dunn, P. J., Pritchard, R. G., & Parr, W. H. (1994). Iowaite, a reinvestigation. Mineralogical Magazine, 58(390), 77-86.; Gliddon, J. (1996) Minerals of the Palabora open pit. British Micromount Society 43:2-7 |
USA (TL) | |
| American Mineralogist: 52: 1261-1271. |
Uzbekistan | |
| Handbook of Mineralogy |
Palabora mine, Loolekop, Phalaborwa, Limpopo Province, South Africa