Amarantite
A valid IMA mineral species - grandfathered
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About Amarantite
Formula:
Fe3+2(SO4)2O · 7H2O
Colour:
Amaranth-red to brownish red and red-orange
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
2.189 - 2.286
Crystal System:
Triclinic
Name:
From the Greek αμάραντος = amaranth, an imaginary red undying flower, in allusion to its colour.
This page provides mineralogical data about Amarantite.
Unique Identifiers
Mindat ID:
182
Long-form identifier:
mindat:1:1:182:9
IMA Classification of Amarantite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Fe3+2O(S6+O4)2·7H2O
Classification of Amarantite
7.DB.30
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
B : With only medium-sized cations; insular octahedra and finite units
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
B : With only medium-sized cations; insular octahedra and finite units
31.9.3.1
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
9 : (AB)(XO4)Zq·xH2O
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
9 : (AB)(XO4)Zq·xH2O
25.10.17
25 : Sulphates
10 : Sulphates of Fe alone
25 : Sulphates
10 : Sulphates of Fe alone
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Ama | 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 Amarantite
Vitreous
Transparency:
Transparent
Colour:
Amaranth-red to brownish red and red-orange
Streak:
Lemon-yellow
Hardness:
2½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
On {010} and {100}, perfect.
On {010} and {100}, perfect.
Density:
2.189 - 2.286 g/cm3 (Measured) 2.14 g/cm3 (Calculated)
Optical Data of Amarantite
Type:
Biaxial (-)
RI values:
nα = 1.516 nβ = 1.598 nγ = 1.621
2V:
Measured: 30° , Calculated: 52°
Max. Birefringence:
δ = 0.105
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
none
Pleochroism:
Visible
Comments:
X = colourless
Y = Light yellow
Z = Reddish brown
Y = Light yellow
Z = Reddish brown
Chemistry of Amarantite
Mindat Formula:
Fe3+2(SO4)2O · 7H2O
Element Weights:
Elements listed:
Crystallography of Amarantite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 8.9 Å, b = 11.56 Å, c = 6.64 Å
α = 95.55°, β = 90.52°, γ = 97.42°
α = 95.55°, β = 90.52°, γ = 97.42°
Ratio:
a:b:c = 0.77 : 1 : 0.574
Unit Cell V:
674.09 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals, to 2 cm, elongated along [001], with dominant {100} and {010}, and square cross section; also flattened [100] and striated on {001}; more than 60 forms recorded; typically in radiating or matted aggregates of needles; columnar or bladed.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
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CIF File Best | x | y | z | a | b | c
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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) |
|---|---|---|---|---|---|---|---|
| 0010666 | Amarantite | Susse P (1968) The crystal structure of amarantite, Fe2(SO4)2O*7H2O Zeitschrift fur Kristallographie 127 261-275 |  | 1968 | Quetena, Chile | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.25 Å | (FFF) |
| 8.69 Å | (FFF) |
| 5.16 Å | (mF) |
| 4.98 Å | (mF) |
| 3.57 Å | (FF) |
| 3.11 Å | (F) |
| 3.05 Å | (FF) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47b : [Sulfates and sulfites] |
Geological Setting:
A secondary mineral formed especially in arid climates.
Type Occurrence of Amarantite
General Appearance of Type Material:
massive
Place of Conservation of Type Material:
BAF, 44700.
Associated Minerals at Type Locality:
Synonyms of Amarantite
Other Language Names for Amarantite
Dutch:Amarantiet
French:Amarantite
German:Amarantit
Norwegian:Amarantitt
Russian:Амарантит
Spanish:Amarantita
Common Associates
Associations Based on Photo Data:
| 24 photos of Amarantite associated with Chalcanthite | CuSO4 · 5H2O |
| 17 photos of Amarantite associated with Copiapite | Fe2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 6 photos of Amarantite associated with Hohmannite | Fe3+2(SO4)2O · 8H2O |
| 4 photos of Amarantite associated with Eriochalcite | CuCl2 · 2H2O |
| 3 photos of Amarantite associated with Alunogen | Al2(SO4)3 · 17H2O |
| 3 photos of Amarantite associated with Kröhnkite | Na2Cu(SO4)2 · 2H2O |
| 2 photos of Amarantite associated with Fibroferrite | Fe3+(SO4)(OH) · 5H2O |
| 2 photos of Amarantite associated with Metahohmannite | Fe3+2(SO4)2O · 4H2O |
| 1 photo of Amarantite associated with Parabutlerite | Fe3+(SO4)(OH) · 2H2O |
| 1 photo of Amarantite associated with Melanterite | Fe2+(H2O)6(SO4) · H2O |
Related Minerals - Strunz-mindat Grouping
| 7.DB.05 | Svyazhinite | (Mg,Mn2+,Ca)(Al,Fe3+)(SO4)2F · 14H2O |
| 7.DB.05 | Aubertite | CuAl(SO4)2Cl · 14H2O |
| 7.DB.05 | Magnesioaubertite | (Mg,Cu)Al(SO4)2Cl · 14H2O |
| 7.DB.10 | Rostite | Al(SO4)(OH) · 5H2O |
| 7.DB.10 | Khademite | Al(SO4)F · 5H2O |
| 7.DB.15 | Jurbanite | Al(SO4)(OH) · 5H2O |
| 7.DB.20 | Minasragrite | (V4+O)(SO4) · 5H2O |
| 7.DB.20 | Anorthominasragrite | (V4+O)(SO4) · 5H2O |
| 7.DB.20 | Orthominasragrite | (V4+O)(SO4) · 5H2O |
| 7.DB.25 | Bobjonesite | (V4+O)(SO4) · 3H2O |
| 7.DB.27 | Karpovite | Tl2VO(SO4)2(H2O) |
| 7.DB.30 | Metahohmannite | Fe3+2(SO4)2O · 4H2O |
| 7.DB.30 | Hohmannite | Fe3+2(SO4)2O · 8H2O |
| 7.DB.35 | Calciocopiapite | CaFe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Zincocopiapite | ZnFe3+4(SO4)6(OH)2 · 18H2O |
| 7.DB.35 | Aluminocopiapite | Al2/3Fe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Copiapite | Fe2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Cuprocopiapite | Cu2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Magnesiocopiapite | MgFe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Ferricopiapite | Fe3+0.67Fe3+4(SO4)6(OH)2 · 20H2O |
Other Information
Notes:
Decomposed by cold water with the formation of an insoluble basic salt. Soluble in HCl.
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 Amarantite
mindat.org URL:
https://www.mindat.org/min-182.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Amarantite
Reference List:
Posnjak, E.; Merwin, H. E. (1922) The system, Fe2O3—SO3—H2O. Journal Of The American Chemical Society, 44 (9). 1965-1994 doi:10.1021/ja01430a016(artificial material)
Bandy, Mark C. (1938) Mineralogy of three sulphate deposits of northern Chile. American Mineralogist, 23 (11) 669-760
Cesbron, Fabien (1964) Contribution à la Minéralogie des sulfates de fer hydratés. Bulletin de Minéralogie, 87 (2) 125-143 doi:10.3406/bulmi.1964.5721
Süsse, P. (1967) Crystal structure of amarantite. Die Naturwissenschaften, 54 (24) 642-643 doi:10.1007/bf01142419
Süsse, P. (1968) The crystal structure of amarantite, Fe2(SO4)2O·7H2O. Zeitschrift für Kristallographie, 127 (1). 261-275 doi:10.1524/zkri.1968.127.1-4.261
Rossman, George R. (1976) The optical spectroscopic comparison of the ferric iron tetrameric clusters in amarantite and leucophosphite. American Mineralogist, 61 (9-10) 933-938
Scordari, F. (1978) The crystal structure of hohmannite, Fe2(H2O)4[(SO4)2O]·4H2O and its relationship to amarantite, Fe2(H2O)4[(SO4)2O]·3H2O. Mineralogical Magazine, 42 (321) 144-146 doi:10.1180/minmag.1978.042.321.24
Localities for Amarantite
Showing 35 localities.
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.
Argentina | |
| Angelelli et al. (1941) |
Australia | |
| Noble R.J et al. (1983) |
Canada | |
| Zodrow (1989) |
Chile | |
| Palache et al. (1951) |
| Kampf +5 other references | |
| Bulletin de Minéralogie 87 (1964) |
| Palache et al. (1951) | |
| Palache et al. (1951) |
| rruff.info/amarantite/ | |
| Bandy (1938) +1 other reference |
| Palache et al. (1951) |
| Samples analysed by Tony Kampf of LAC ... |
| Palache et al. (1951) |
| Maksaev et al. (2010) |
| Peter G. Seroka collection |
China | |
| Liu et al. (2018) |
Greece | |
| Rieck et al. (2018) |
| no description given yet] +1 other reference | |
Iran | |
| Bariand et al. (1973) +1 other reference |
Italy | |
| Fernando Caboni et al. (2024) |
| Fernando Caboni et al. (2024) | |
| Quagliarella (1966) |
Norway | |
| Selbekk et al. (2010) |
Peru | |
| Atchley (1956) |
Russia | |
| Kudrin et al. (2021) |
Slovakia | |
| Szakáll et al. (2014) |
| Szakáll et al. (2014) | |
| Duda |
Spain | |
| Jose Miguel Sola collection |
USA | |
| Schairer et al. (1924) +1 other reference |
| Schairer et al. (1924) +2 other references | |
| Northrop et al. (1996) |
| Northrop et al. (1996) | |
| Roberts et al. (1965) |
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Queténa Mine, Toki Cu deposit, Chuquicamata District, Calama, El Loa Province, Antofagasta, Chile