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Mg6Fe3+2(OH)16Cl2 · 4H2O
bluish green
Specific Gravity:
Crystal System:
For the state of the 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).

Classification of Iowaite


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 : Miscellaneous

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
11 : Halides of Fe and Ni

Physical Properties of Iowaite

bluish green
1½ on Mohs scale
Perfect basal cleavage
2.11(2) g/cm3 (Measured)    

Optical Data of Iowaite

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.
Surface Relief:

Chemical Properties of Iowaite

Mg6Fe3+2(OH)16Cl2 · 4H2O

Crystallography of Iowaite

Crystal System:
Class (H-M):
3m (3 2/m) - Hexagonal Scalenohedral
Space Group:
Cell Parameters:
a = 3.119(5) Å, c = 24.25(2) Å
a:c = 1 : 7.775
Unit Cell V:
204.30 ų (Calculated from Unit Cell)
Call parameters from powder diffraction data

Occurrences of Iowaite

Paragenetic Mode(s):

Type Occurrence of Iowaite

General Appearance of Type Material:
Platy crystals 2-3mm in size
Geological Setting of Type Material:
Altered serpentinite in precambrian basement

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

Other Members of this group:
DesautelsiteMg6Mn3+2(OH)16[CO3] · 4H2O
DroninoiteNi6Fe2+3(OH)16Cl2 · 4H2O
HydrotalciteMg6Al2(OH)16[CO3] · 4H2O
MeixneriteMg6Al2(OH)16(OH)2 · 4H2O
PyroauriteMg6Fe3+2(OH)16[CO3] · 4H2O
ReevesiteNi6Fe3+2(OH)16(CO3) · 4H2O
StichtiteMg6Cr3+2(OH)16[CO3] · 4H2O
TakoviteNi6Al2(OH)16[CO3] · 4H2O
WoodalliteMg6Cr2(OH)16Cl2 · 4H2O

Common Associates

Associated Minerals Based on Photo Data:
Magnetite8 photos of Iowaite associated with Magnetite on
Valleriite7 photos of Iowaite associated with Valleriite on
Calcite6 photos of Iowaite associated with Calcite on
Fluorapatite4 photos of Iowaite associated with Fluorapatite on
Lizardite2 photos of Iowaite associated with Lizardite on
Gypsum1 photo of Iowaite associated with Gypsum on
Brucite1 photo of Iowaite associated with Brucite on
Pentlandite1 photo of Iowaite associated with Pentlandite on
Woodallite1 photo of Iowaite associated with Woodallite on
Muscovite1 photo of Iowaite associated with Muscovite on

Related Minerals - Nickel-Strunz Grouping

4.FL.05WoodalliteMg6Cr2(OH)16Cl2 · 4H2O
4.FL.05MeixneriteMg6Al2(OH)16(OH)2 · 4H2O
4.FL.05MuskoxiteMg7Fe4O13 · 10H2O
4.FL.10HydrocalumiteCa4Al2(OH)12(Cl,CO3,OH)2 · 4H2O
4.FL.15KuzeliteCa4Al2(OH)12[SO4] · 6H2O
4.FL.20Aurorite(Mn2+,Ag,Ca)Mn4+3O7 · 3H2O
4.FL.20Chalcophanite(Zn,Fe,Mn)Mn3O7 · 3H2O
4.FL.20ErnienickeliteNiMn3O7 · 3H2O
4.FL.20Jianshuiite(Mg,Mn,Ca)Mn3O7 · 3H2O
4.FL.30Asbolane(Ni,Co)2-xMn4+(O,OH)4 · nH2O
4.FL.35BuseriteNa4Mn14O27 · 21H2O
4.FL.40Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
4.FL.40Takanelite(Mn,Ca)Mn4O9 · H2O
4.FL.45Birnessite(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
4.FL.55CianciulliiteMn(Mg,Mn)2Zn2(OH)10 · 2-4H2O
4.FL.60JenseniteCu3[TeO6] · 2H2O
4.FL.65LeisingiteCuMg2Te6+O6 · 6H2O
4.FL.70Akdalaite5Al2O3 · H2O
4.FL.75CafetiteCaTi2O5 · H2O

Related Minerals - Hey's Chemical Index of Minerals Grouping

8.11.2HydromolysiteFeCl3 · 6H2O
8.11.3RokühniteFeCl2 · 2H2O
8.11.9NickelbischofiteNiCl2 · 6H2O

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
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 URL:
Please feel free to link to this page.

Localities for Iowaite

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
  • Western Australia
    • Wiluna Shire
      • Lake Way Station
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
      • Mount Keith
[AmMin 87:182]
  • Québec
    • Estrie
      • Les Sources RCM
        • Asbestos
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
  • Mariana forearc
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
  • Upper Silesia (Śląskie)
    • Upper Silesian Coal Basin
      • Rybnik Coal Area
        • Radlin
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
    • Zawiercie District
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
  • Eastern-Siberian Region
    • Prebaikalia (Pribaikal'e)
      • Irkutskaya Oblast'
        • Zheleznogorsk (Korshunikha)
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.
    • Sakha Republic (Saha Republic; Yakutia)
      • Daldyn-Alakit kimberlite field
        • Daldyn
Pavel M. Kartashov data
    • Taymyrskiy Autonomous Okrug
      • Taimyr Peninsula
        • Putoran Plateau
          • Noril'sk
            • Talnakh Cu-Ni Deposit
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
  • Western-Siberian Region
    • Altai Republic (Gorno-Altayskaya Autonomous Oblast')
      • Ust'-Koksa district
Igor V. Pekov data
South Africa
  • Limpopo Province
    • Phalaborwa
      • Loolekop
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
  • Iowa
    • Sioux Co.
American Mineralogist: 52: 1261-1271.
  • Tashkent Viloyati (Toshkent)
Handbook of Mineralogy
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