Iowaite
A valid IMA mineral species
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About Iowaite
Flag of Iowa, USA
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).
Unique Identifiers
Mindat ID:
2038
Long-form identifier:
mindat:1:1:2038:7
GUID
(UUID V4):
(UUID V4):
eed77052-7ca7-4f15-9638-4e1d295fe87b
IMA Classification of Iowaite
Approved
First published:
1967
Classification of Iowaite
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
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Iow | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Iow | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
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
Chemistry of Iowaite
Mindat 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 = 3.1077(9) Å, c = 23.885(13) Å
Ratio:
a:c = 1 : 7.686
Unit Cell V:
199.78 ų
Z:
3
Comment:
updated cell parameters from Zhitova et al. (2023); formerly here: a=3.119(5), c=24.25(2) (also from a powder diffraction data)
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0000189 | Iowaite | Allmann R, Donnay J D H (1969) About the structure of iowaite American Mineralogist 54 296-299 |  | 1969 | 0 | 293 | |
| 0014506 | Iowaite | Braithwaite R S W, Dunn P J, Pritchard R G, Paar W H (1994) Iowaite, a re-investigation Mineralogical Magazine 58 79-85 | | 1994 | Palabora open pit mine, Phalaborwa, Transvaal | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.109 Å | (100) |
| 4.047 Å | (40) |
| 2.363 Å | (27) |
| 2.019 Å | (23) |
| 2.639 Å | (17) |
| 1.530 Å | (13) |
| 1.560 Å | (8) |
Comments:
Sioux Co., Iowa, USA. Data from the type description. The type specimen was remeasured about 27 years later (Braithwaite 1994) and a shift in the data was measured, likely due to dehydration.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 13 : Hadean serpentinization | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 38 : Ophiolites | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
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
| Chromium-bearing 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 | Ni6Fe3+2(OH)16Cl2 · 4H2O | Trig. 3m (3 2/m) : R3m |
| Hydrotalcite | Mg6Al2(CO3)(OH)16 · 4H2O | Trig. 3m (3 2/m) : R3m |
| Hydrotalcite-3R | Mg6Al2(CO3)(OH)16 · 4H2O | Trig. 3m (3 2/m) : R3m |
| Kaznakhtite | Ni6Co3+2(CO3)(OH)16 · 4H2O | Trig. 3 : R3 |
| 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. 3m (3 2/m) : R3m |
| Stichtite | Mg6Cr3+2(OH)16[CO3] · 4H2O | Trig. 3m (3 2/m) : R3m |
| Takovite | Ni6Al2(OH)16[CO3] · 4H2O | Trig. 3m (3 2/m) : R3m |
| UM2002-02-COH:FeNi | (Fe2+,Ni)6Fe3+2(CO3)(OH)16 · 4H2O | |
| Woodallite | Mg6Cr2(OH)16Cl2 · 4H2O | Trig. 3m (3 2/m) : R3m |
Common Associates
Associated Minerals Based on Photo Data:
| 25 photos of Iowaite associated with Calcite | CaCO3 |
| 16 photos of Iowaite associated with Magnetite | Fe2+Fe3+2O4 |
| 10 photos of Iowaite associated with Valleriite | (Fe2+,Cu)4(Mg,Al)3S4(OH,O)6 |
| 8 photos of Iowaite associated with Hetaerolite | ZnMn2O4 |
| 6 photos of Iowaite associated with Chalcopyrite | CuFeS2 |
| 6 photos of Iowaite associated with Cubanite | CuFe2S3 |
| 4 photos of Iowaite associated with Fluorapatite | Ca5(PO4)3F |
| 3 photos of Iowaite associated with Gypsum | CaSO4 · 2H2O |
| 2 photos of Iowaite associated with Lizardite | Mg3(Si2O5)(OH)4 |
| 2 photos of Iowaite associated with Kuliginite | Fe3Mg(OH)6Cl2 |
Related Minerals - Strunz-mindat Grouping
| 4.FL. | Trébeurdenite | Fe2+2Fe3+4O2(OH)10CO3 · 3H2O |
| 4.FL. | Mariakrite | [Ca4Al2(OH)12(H2O)4][Fe2S4] |
| 4.FL.05 | Woodallite | Mg6Cr2(OH)16Cl2 · 4H2O |
| 4.FL.05 | Jamborite | Ni2+1-xCo3+x(OH)2-x(SO4)x · nH2O |
| 4.FL.05 | Meixnerite | Mg6Al2(OH)16(OH)2 · 4H2O |
| 4.FL.05 | Muskoxite | Mg7Fe4O13 · 10H2O |
| 4.FL.05 | Fougèrite | Fe2+4Fe3+2(OH)12[CO3] · 3H2O |
| 4.FL.05 | Mössbauerite | Fe3+6O4(OH)8[CO3] · 3H2O |
| 4.FL.05 | Dritsite | Li2Al4(OH)12Cl2 · 3H2O |
| 4.FL.10 | Hydrocalumite | Ca4Al2(OH)12(Cl,CO3,OH)2 · 4H2O |
| 4.FL.15 | Kuzelite | Ca4Al2(OH)12[SO4] · 6H2O |
| 4.FL.20 | Aurorite | Mn2+Mn4+3O7 · 3H2O |
| 4.FL.20 | Chalcophanite | ZnMn4+3O7 · 3H2O |
| 4.FL.20 | Ernienickelite | NiMn3O7 · 3H2O |
| 4.FL.20 | Jianshuiite | (Mg,Mn,Ca)Mn3O7 · 3H2O |
| 4.FL.25 | Woodruffite | Zn2+x/2(Mn4+1-xMn3+x)O2 · yH2O |
| 4.FL.30 | Asbolane | (Ni,Co)2-xMn4+(O,OH)4 · nH2O |
| 4.FL.30 va | Lampadite | Cu, Mn, O, H |
| 4.FL.35 | Buserite | Na4Mn14O27 · 21H2O |
| 4.FL.40 | Ranciéite | (Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O |
| 4.FL.40 | Takanelite | (Mn,Ca)Mn4O9 · H2O |
| 4.FL.45 | Birnessite | (Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O |
| 4.FL.55 | Cianciulliite | Mn(Mg,Mn)2Zn2(OH)10 · 2-4H2O |
| 4.FL.60 | Jensenite | Cu3[TeO6] · 2H2O |
| 4.FL.65 | Leisingite | Cu2MgTe6+O6 · 6H2O |
| 4.FL.70 | Akdalaite | Al10O14(OH)2 |
| 4.FL.75 | Cafetite | CaTi2O5 · H2O |
| 4.FL.80 | Mourite | UMo5O12(OH)10 |
| 4.FL.85 | Deloryite | Cu4(UO2)(MoO4)2(OH)6 |
| 4.FL.90 | Lagalyite | Ca2xMn1-xO2 · 1.5-2H2O |
| 4.FL.95 | Tunnerite (of Cornu) | |
| 4.FL.100 | Carbocalumite | Ca4Al2(OH)12(CO3) · 6H2O |
| 4.FL.100 | Mampsisite | Ca4Al2(CO3)(OH)12 · 5H2O |
Other Information
Thermal Behaviour:
In DTA measurements, a large endothermic reaction occurs between 315°C and 350°C, representing a collapse of the iowaite structure. The material changes in color from light tan to dark brown, water is evolved, and periclase is formed.
Notes:
Insoluble in water and readily soluble in mineral acids.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Iowaite
mindat.org URL:
https://www.mindat.org/min-2038.html
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References for Iowaite
Reference List:
Kohls, D. W., Rodda, J. L. (1967) Iowaite, a new hydrous magnesium hydroxide-ferric oxychloride from the Precambrian of Iowa. American Mineralogist, 52 (9-10) 1261-1271
Jambor, John L., Roberts, Andrew C., Vanko, David A. (1994) New Mineral Names. American Mineralogist, 79 (9-10) 1009-1014
Localities for Iowaite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Atlantic Ocean | |
| Plas (1997) | |
| Moll et al. (2007) |
Australia | |
| Barnes et al. (2009) |
| Disseminated and Massive Nickel ... +2 other references |
| Grguric et al. (2013) | |
| Wilson et al. (2014) | |
| [AmMin 87:182] | |
Canada | |
| Franchuk et al. (2016) |
| Jordan E. Laarman (2014) |
| Jordan E. Laarman (2014) | |
| Horváth et al. (2013) |
China | |
| Zhu et al. (2015) |
France | |
| Monnin et al. (2014) |
Oman | |
| Chavagnac et al. (2013) |
Pacific Ocean | |
| Plas (1997) |
| Heling et al. (1992) |
| Wheat et al. (2008) | |
Poland | |
| Łukasz Kruszewski (2012) |
| Koszowska E. |
Russia | |
| Zhitova et al. (2020) |
| Igor V. Pekov data | |
| Mazurov et al. (2007) +1 other reference |
| Mineralogical Society of America - ... +1 other reference |
| Pavel.M. Kartashov (n.d.) +5 other references |
South Africa | |
| Braithwaite et al. (1994) +2 other references |
Spain | |
| Evans et al. (2012) |
USA (TL) | |
| American Mineralogist: 52: 1261-1271. |
| Modris Baum collection - Joy Desor ... |
Uzbekistan | |
| Mineralogical Society of America - ... |
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Palabora Mine, Phalaborwa, Ba-Phalaborwa Local Municipality, Mopani District Municipality, Limpopo, South Africa