Coquimbite (original) (raw)
A valid IMA mineral species - grandfathered
About CoquimbiteHide
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Formula:
AlFe3(SO4)6(H2O)12 · 6H2O
Formerly given as Fe2-xAlx(SO4)3.9H2O (x ~0.5) or even Fe2(SO4)3.9H2O; redefined by IMA in 2019 (Al is essential)
Colour:
Light violet to purple, Greenish white, Bluish white, Yellowish white, Brownish white
Lustre:
Sub-Vitreous, Resinous, Waxy, Greasy
Name:
Named in 1841 by August Breithaupt for the type locality in the province of Coquimbo, Chile
Visually indistinguishable from aluminocoquimbite.
Coquimbite and paracoquimbite are structurally homeotypic.
Most (or all, if the species is truly coquimbite) samples carry Al, with variable Al:Fe ratio. It is now (2019) proved that Al is essential. Three metal sites, all with octahedral coordination, are non-equivalent. M(1) site, usually fully occupied by Al, is coordinated by water, M(2) - exclusively by the sulfate groups, while M(3) is surrounded by three oxygens of the sulfate groups and three belonging to water moleculess. M(2) and M(3) sites are dominated by Fe. There are M(2)M(3)2(SO4)6(H2O)6 clusters. Sulfate groups participating in the formation of these clusters are corner-sharing. Additional 6 water groups are held only be hydrogen bonding. Interaction of Fe3(SO4)6(H2O)6 clusters via hydrogen bonds gives rise to discontinuous zig-zag chains along [001]. Further hydrogen bond interaction of these chains with isolated Al(H2O)6 octahedra produces cages containing interstitial water. An interesting structural features is a cyclohexane-like chair conformation of these water molecules, also observed in aluminocoquimbite.
Compare the visually similar 'UM1988-20-SO:FeH'.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:1126:2
82fbe8af-38be-41c4-9d4e-c38ac40598aa
IMA Classification of CoquimbiteHide
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Approved, 'Grandfathered' (first described prior to 1959)
Approval history:
redefinition code: IMA 19-F
Classification of CoquimbiteHide
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7.CB.55
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
B : With only medium-sized cations
29.8.3.1
29 : HYDRATED ACID AND NORMAL SULFATES
8 : A2(XO4)3·H2O
25.10.9
25 : Sulphates
10 : Sulphates of Fe alone
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Coq | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of CoquimbiteHide
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Sub-Vitreous, Resinous, Waxy, Greasy
Colour:
Light violet to purple, Greenish white, Bluish white, Yellowish white, Brownish white
Cleavage:
Imperfect/Fair
fair/imperfect on [1011]
very poor/difficult on {1010}
Density:
2.11(1) g/cm3 (Measured) 2.12 g/cm3 (Calculated)
Comment:
Dana, 7th ed. gives calculated density as 2.137.
Optical Data of CoquimbiteHide
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RI values:
_n_ω = 1.539 _n_ε = 1.548
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Optical Extinction:
Parallel
Pleochroism:
Non-pleochroic
Chemistry of CoquimbiteHide
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Mindat Formula:
AlFe3(SO4)6(H2O)12 · 6H2O
Formerly given as Fe2-xAlx(SO4)3.9H2O (x ~0.5) or even Fe2(SO4)3.9H2O; redefined by IMA in 2019 (Al is essential)
Crystallography of CoquimbiteHide
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Class (H-M):
3_m_ _(_32/m ) - Hexagonal Scalenohedral
Cell Parameters:
a = 10.922(9) Å, c = 17.084(14) Å
Unit Cell V:
1,764.92 ų (Calculated from Unit Cell)
Morphology:
Short prismatic [0001] with {1010} and {1120} to pyramidal crystals {1011}. Massive, granular.
Crystal StructureHide
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| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0000211 | Coquimbite | Fang J H, Robinson P D (1970) Crystal structures and mineral chemistry of hydrated ferric sulfates. I. The crystal structure of coquimbite American Mineralogist 55 1534-1540 |  |
1970 | 0 | 293 | |
| 0006334 | Coquimbite | Demartin F, Castellano C, Gramaccioli C M, Campostrini I (2010) Aluminum-for-iron substitution, hydrogen bonding, and a novel structure-type in coquimbite-like minerals The Canadian Mineralogist 48 323-333 | 2010 | La Alcaparrosa, Chile | 0 | 293 | |
| 0006335 | Coquimbite | Demartin F, Castellano C, Gramaccioli C M, Campostrini I (2010) Aluminum-for-iron substitution, hydrogen bonding, and a novel structure-type in coquimbite-like minerals The Canadian Mineralogist 48 323-333 | 2010 | the Dexter No. 7 mine, Calf Mesa, San Rafael Swell, Utah, USA | 0 | 293 | |
| 0006336 | Coquimbite | Demartin F, Castellano C, Gramaccioli C M, Campostrini I (2010) Aluminum-for-iron substitution, hydrogen bonding, and a novel structure-type in coquimbite-like minerals The Canadian Mineralogist 48 323-333 | 2010 | Alum Grotto, Vulcano, Aeolian Islands, Sicily, Italy | 0 | 293 | |
| 0007144 | Coquimbite | Majzlan J, Navrotsky A, McCleskey R B, Alpers C N (2006) Thermodynamic properties and crystal structure refinement of ferricopiapite, coquimbite, rhomboclase, and Fe2(SO4)3(H2O)5 European Journal of Mineralogy 18 175-186 | 2006 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
Epitaxial Relationships of CoquimbiteHide
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Epitaxy Comments:
Paracoquimbite in parallel position. Lamellar intergrowths on {0001}, or as scepter-like overgrowths.
X-Ray Powder DiffractionHide
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Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.28 Å | (80) |
| 5.47 Å | (60) |
| 4.60 Å | (60) |
| 3.64 Å | (60) |
| 3.50 Å | (50) |
| 3.36 Å | (100) |
| 2.77 Å | (50) |
| 2.76 Å | (80) |
Geological EnvironmentHide
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Geological Setting:
Secondary weathering zone of iron sulfide deposits in arid regions. Rarely in fumaroles.
Type Occurrence of CoquimbiteHide
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Place of Conservation of Type Material:
Mining Academy, Freiberg, Germany 18558; neotype: U.S. National Museum, Washington DC, USA, catalogue number 12548 (Tierra Amarilla material; Rose, 1833; Fang and Robinson, 1970)
Synonyms of CoquimbiteHide
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Other Language Names for CoquimbiteHide
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Varieties of CoquimbiteHide
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| Aluminous Coquimbite | An aluminous variety of coquimbite formed as a by-product of a burning pyritic orebody. |
|---|
Relationship of Coquimbite to other SpeciesHide
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Other Members of this group:
Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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| 7.CB. | Sarvodaite | Al2(SO4)3 · 5H2O | Mon. 2/m : _P_21/m |
|---|---|---|---|
| 7.CB.02 | Voudourisite | CdSO4 · H2O | Mon. 2/m : _P_21/m |
| 7.CB.05 | Dwornikite | Ni(SO4) · H2O | Mon. 2/m : _B_2/b |
| 7.CB.05 | Gunningite | ZnSO4 · H2O | Mon. 2/m : _B_2/b |
| 7.CB.05 | Kieserite | MgSO4 · H2O | Mon. 2/m : _B_2/b |
| 7.CB.05 | Poitevinite | (Cu,Fe)SO4 · H2O | Tric. 1 : _P_1 |
| 7.CB.05 | Szmikite | MnSO4 · H2O | Mon. 2/m : _B_2/b |
| 7.CB.05 | Szomolnokite | FeSO4 · H2O | Mon. 2/m : _B_2/b |
| 7.CB.05 | Cobaltkieserite | CoSO4 · H2O | Mon. 2/m : _B_2/b |
| 7.CB.07 | Sanderite | MgSO4 · 2H2O | Orth. 222 : _P_212121 |
| 7.CB.10 | Bonattite | CuSO4 · 3H2O | Mon. m : B b |
| 7.CB.12 | Belogubite | CuZn(SO4)2 · 10H2O | Tric. 1 : _P_1 |
| 7.CB.15 | Aplowite | (Co,Mn,Ni)SO4 · 4H2O | Mon. 2/m |
| 7.CB.15 | Boyleite | (Zn,Mg)SO4 · 4H2O | Mon. 2/m : _P_21/b |
| 7.CB.15 | Ilesite | Mn2+(SO4) · 4H2O | Mon. 2/m |
| 7.CB.15 | Rozenite | FeSO4 · 4H2O | Mon. 2/m : _P_21/b |
| 7.CB.15 | Starkeyite | MgSO4 · 4H2O | Mon. 2/m : _P_21/b |
| 7.CB.15 | Drobecite | CdSO4 · 4H2O | Mon. 2/m : _P_21/m |
| 7.CB.15 | Cranswickite | MgSO4 · 4H2O | Mon. m : B b |
| 7.CB.20 | Chalcanthite | CuSO4 · 5H2O | Tric. 1 : _P_1 |
| 7.CB.20 | Jôkokuite | MnSO4 · 5H2O | Tric. 1 : _P_1 |
| 7.CB.20 | Pentahydrite | MgSO4 · 5H2O | Tric. 1 : _P_1 |
| 7.CB.20 | Siderotil | FeSO4 · 5H2O | Tric. |
| 7.CB.25 | Bianchite | Zn(SO4) · 6H2O | Mon. 2/m : _P_2/m |
| 7.CB.25 | Chvaleticeite | Mn(SO4) · 6H2O | Mon. 2/m : _B_2/b |
| 7.CB.25 | Ferrohexahydrite | FeSO4 · 6H2O | Mon. 2/m : _B_2/b |
| 7.CB.25 | Hexahydrite | MgSO4 · 6H2O | Mon. 2/m : _P_2/m |
| 7.CB.25 | Moorhouseite | Co(SO4) · 6H2O | Mon. 2/m : _B_2/b |
| 7.CB.25 | Nickelhexahydrite | Ni(SO4) · 6H2O | Mon. 2/m : _B_2/b |
| 7.CB.30 | Retgersite | NiSO4 · 6H2O | Tet. 422 : _P_41212 |
| 7.CB.35 | Bieberite | CoSO4 · 7H2O | Mon. 2/m : _P_2/m |
| 7.CB.35 | Boothite | CuSO4 · 7H2O | Mon. 2/m : _P_21/b |
| 7.CB.35 | Mallardite | MnSO4 · 7H2O | Mon. 2/m : _P_2/m |
| 7.CB.35 | Melanterite | Fe2+(H2O)6SO4 · H2O | Mon. 2/m : _P_21/b |
| 7.CB.35 | Zincmelanterite | (Zn,Cu,Fe)SO4 · 7H2O | Mon. 2/m : _P_21/b |
| 7.CB.35 | Alpersite | (Mg,Cu)(SO4) · 7H2O | Mon. 2/m : _P_21/b |
| 7.CB.40 | Epsomite | MgSO4 · 7H2O | Orth. 222 : _P_212121 |
| 7.CB.40 | Goslarite | ZnSO4 · 7H2O | Orth. 222 : _P_212121 |
| 7.CB.40 | Morenosite | NiSO4 · 7H2O | Orth. 222 : _P_212121 |
| 7.CB.45 | Alunogen | Al2(SO4)3 · 17H2O | Tric. 1 : _P_1 |
| 7.CB.45 | Meta-alunogen | Al2(SO4)3 · 12H2O | Orth. |
| 7.CB.50 | Aluminocoquimbite | Al2Fe2(SO4)6(H2O)12 · 6H2O | Trig. 3_m_ _(_32/m ) : P_31_c |
| 7.CB.50 | Lazaridisite | 3CdSO4 · 8H2O | Mon. 2/m : _B_2/b |
| 7.CB.52 | Pararaisaite | CuMg[Te6+O4(OH)2] · 6H2O | Mon. 2/m : _P_21/b |
| 7.CB.55 | Paracoquimbite | Fe4(SO4)6(H2O)12 · 6H2O | Trig. 3 : _R_3 |
| 7.CB.55 | Rhomboclase | (H5O2)Fe3+(SO4)2 · 2H2O | Orth. m m m _(_2/_m_2/_m_2/m ) : P n m a |
| 7.CB.55 | Raisaite | CuMg[Te6+O4(OH)2] · 6H2O | Mon. 2/m : _B_2/b |
| 7.CB.57 | Caichengyunite | Fe2+3Al2(SO4)6 · 30H2O | Mon. |
| 7.CB.60 | Kornelite | Fe2(SO4)3 · 7H2O | Mon. 2/m : _P_21/m |
| 7.CB.65 | Quenstedtite | Fe2(SO4)3 · 11H2O | Tric. 1 : _P_1 |
| 7.CB.70 | Lausenite | Fe2(SO4)3 · 5H2O | Mon. 2/m : _P_21/m |
| 7.CB.75 | Lishizhenite | ZnFe2(SO4)4 · 14H2O | Tric. 1 : _P_1 |
| 7.CB.75 | Römerite | Fe2+Fe3+2(SO4)4 · 14H2O | Tric. 1 : _P_1 |
| 7.CB.80 | Ransomite | CuFe2(SO4)4 · 6H2O | Mon. 2/m : _P_21/b |
| 7.CB.85 | Apjohnite | Mn2+Al2(SO4)4 · 22H2O | Mon. 2/m : _P_21/b |
| 7.CB.85 | Bílinite | Fe2+Fe3+2(SO4)4 · 22H2O | Mon. 2/m : _P_21/b |
| 7.CB.85 | Dietrichite | (Zn,Fe2+,Mn2+)Al2(SO4)4 · 22H2O | Mon. 2/m : _P_21/b |
| 7.CB.85 | Halotrichite | FeAl2(SO4)4 · 22H2O | Mon. 2 : _P_2 |
| 7.CB.85 | Pickeringite | MgAl2(SO4)4 · 22H2O | Mon. 2/m : _P_21/b |
| 7.CB.85 | Redingtonite | (Fe2+,Mg,Ni)(Cr,Al)2(SO4)4 · 22H2O | Mon. 2 |
| 7.CB.85 | Wupatkiite | (Co,Mg,Ni)Al2(SO4)4 · 22H2O | Mon. 2/m : _P_21/b |
| 7.CB.90 | Meridianiite | MgSO4 · 11H2O | Tric. 1 : _P_1 |
Fluorescence of CoquimbiteHide
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Other InformationHide
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Notes:
Soluble in cold water and cold mineral acids; astringent taste, efforesces in dry air as a white powder; heating a water solution causes decomposition of the solution with precipitation of hydrated ferric oxide
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 CoquimbiteHide
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References for CoquimbiteHide
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Reference List:
Demartin, F., Castellano, C., Gramaccioli, C. M., Campostrini, I. (2010) ALUMINUM-FOR-IRON SUBSTITUTION, HYDROGEN BONDING, AND A NOVEL STRUCTURE-TYPE IN COQUIMBITE-LIKE MINERALS. The Canadian Mineralogist, 48 (2) 323-333 doi:10.3749/canmin.48.2.323
Majzlan, Juraj, Ðorđević, Tamara, Kolitsch, Uwe, Schefer, Jürg (2010) Hydrogen bonding in coquimbite, nominally Fe2(SO4)3·9H2O, and the relationship between coquimbite and paracoquimbite. Mineralogy and Petrology, 100 (3) 241-248 doi:10.1007/s00710-010-0128-4
Localities for CoquimbiteHide
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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.
Locality ListHide
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- 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.