Ernstite
A valid IMA mineral species
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About Ernstite
Formula:
(Mn2+,Fe3+)Al(PO4)(OH,O)2 ¡ H2O
Colour:
Yellow-brown
Hardness:
3 - 3½
Specific Gravity:
3.07
Crystal System:
Monoclinic
Name:
Named for Dr. Karl Theodor Heinrich Ernst ((3 January 1904, Uelzen, Germany - 26 February 1983, Erlangen, Germany), professor of mineralogy, Erlangen University, Erlangen, Germany.
Ernstite was named on oxidized eosphorite. As eosphorite has by definition Mn2+ > Fe2+, then the ferric component could never be greater than 50 mole percent and is therefore only a named variety. Some of the water molecule occupancy in the empirical eosphorite formula may be converted to hydroxyl in the same ratio as the oxidized Fe. The above formula shows only hydroxyl plus oxygen in the formula instead of (OH, O, H20) as though oxygen and hydroxyl were in equivalent sites without any residual water in the structure. If the actual original material were a childrenite, it would be possible to have a ferric-dominant oxidized member of the series. No name has been proposed for oxidized childrenite, but any such new name would have to have ferric iron > 50 mole percent of the M site. Ernstite should be re-investigated.
Unique Identifiers
Mindat ID:
1404
Long-form identifier:
mindat:1:1:1404:1
GUID
(UUID V4):
(UUID V4):
6d81160b-4d9a-4f18-b88f-64af7c53b12d
IMA Classification of Ernstite
Approved
IMA Formula:
(Mn2+,Fe3+)Al(PO4)(OH,O)2
Approval year:
1970
First published:
1970
Approval history:
IMA1970-012
Classification of Ernstite
8.DD.20
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
D : With only medium-sized cations, (OH, etc.):RO4= 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
D : With only medium-sized cations, (OH, etc.):RO4= 2:1
42.7.1.3
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
7 : (AB)2(XO4)Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
7 : (AB)2(XO4)Zq·xH2O
19.12.56
19 : Phosphates
12 : Phosphates of Mn
19 : Phosphates
12 : Phosphates of Mn
Mineral Symbols
As of 2021 there are now IMAâCNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Ens | IMAâCNMNC | Warr, L.N. (2021). IMAâCNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Ernstite
Transparency:
Translucent
Colour:
Yellow-brown
Hardness:
3 - 3½ on Mohs scale
Cleavage:
Distinct/Good
Very Good on {100}
Good on {010}
Very Good on {100}
Good on {010}
Density:
3.07 g/cm3 (Measured) 3.086 g/cm3 (Calculated)
Optical Data of Ernstite
Type:
Biaxial (-)
RI values:
nα = 1.678 nβ = 1.706 nγ = 1.721
2V:
Measured: 74° , Calculated: 70°
Max Birefringence:
δ = 0.043
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:
High
Dispersion:
r > v
Pleochroism:
Visible
Comments:
X= yellowish-brown
Y= red-brown
Z= pale yellow
Y= red-brown
Z= pale yellow
Chemistry of Ernstite
Mindat Formula:
(Mn2+,Fe3+)Al(PO4)(OH,O)2 ¡ H2O
Crystallography of Ernstite
Crystal System:
Monoclinic
Cell Parameters:
a = 13.32(1) Å, b = 10.497(5) Å, c = 6.969(4) Å
β = 90.37°
β = 90.37°
Ratio:
a:b:c = 1.269 : 1 : 0.664
Unit Cell V:
974.39 Ă
Âł (Calculated from Unit Cell)
Z:
8
Morphology:
Radial aggregates
Comment:
Point Group: 2/m or m.; Space Group: A2/a or Aa.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.364 Ă | (40) |
| 3.516 Ă | (40) |
| 2.836 Ă | (80) |
| 2.829 Ă | (100) |
| 2.438 Ă | (50) |
| 2.424 Ă | (40) |
| 2.001 Ă | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-đ subsurface aqueous alteration (see also #23) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] |
Type Occurrence of Ernstite
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 145620.
Geological Setting of Type Material:
Oxidized granitic pegmatite
Associated Minerals at Type Locality:
Reference:
Seeliger, E., MĂźcke, A. (1970) Ernstit, ein neues Mn2+-Fe3+-Al-phosphat und seine beziehungen zum eosphorit. Neues Jahrbuch fĂźr Mineralogie, Monatshefte: 1970: 289-298.
Synonyms of Ernstite
Other Language Names for Ernstite
Common Associates
Associated Minerals Based on Photo Data:
| 6 photos of Ernstite associated with Eosphorite | Mn2+Al(PO4)(OH)2 ¡ H2O |
| 2 photos of Ernstite associated with Kosnarite | KZr2(PO4)3 |
| 1 photo of Ernstite associated with Chlorapatite | Ca5(PO4)3Cl |
Related Minerals - Strunz-mindat Grouping
| 8.DD. | Bettertonite | [Al6(AsO4)3(OH)9(H2O)5] ¡ 11H2O |
| 8.DD. | Penberthycroftite | [Al6(AsO4)3(OH)9(H2O)5] ¡ 8H2O |
| 8.DD. | Vargite | Cu2Mn3(AsO4)2(OH)4(H2O)4 |
| 8.DD. | Galeaclolusite | Al6(AsO4)3(OH)9(H2O)4 ¡ 8H2O |
| 8.DD.05 | Chenevixite | Cu2Fe3+2(AsO4)2(OH)4 |
| 8.DD.05 | Luetheite | Cu2Al2(AsO4)2(OH)4 |
| 8.DD.10 | Akrochordite | (Mn2+,Mg)5(AsO4)2(OH)4 ¡ 4H2O |
| 8.DD.10 | Guanacoite | Cu2Mg3(AsO4)2(OH)4 ¡ 4H2O |
| 8.DD.15 | Aheylite | (Fe2+,Zn)Al6(PO4)4(OH)8 ¡ 4H2O |
| 8.DD.15 | Chalcosiderite | CuFe3+6(PO4)4(OH)8 ¡ 4H2O |
| 8.DD.15 | Coeruleolactite | |
| 8.DD.15 | Faustite | ZnAl6(PO4)4(OH)8 ¡ 4H2O |
| 8.DD.15 | Planerite | Al6(PO4)2(PO3OH)2(OH)8 ¡ 4H2O |
| 8.DD.15 | Turquoise | CuAl6(PO4)4(OH)8 ¡ 4H2O |
| 8.DD.15 | Afmite | Al3(OH)4(H2O)3(PO4)(PO3OH) ¡ H2O |
| 8.DD.15 | UM1981-32-PO:FeH | Fe2+Fe3+6(PO4)4-x[PO3(OH)]x(OH)8 ¡ 4H2O |
| 8.DD.20 | Childrenite | Fe2+Al(PO4)(OH)2 ¡ H2O |
| 8.DD.20 | Eosphorite | Mn2+Al(PO4)(OH)2 ¡ H2O |
| 8.DD.20 | Lefontite | Fe2Al2Be(PO4)2(OH)6 |
| 8.DD.25 | Kobokoboite | Al6(PO4)4(OH)6 ¡ 11H2O |
| 8.DD.30 | Smamite | Ca2Sb(OH)4[H(AsO4)2] ¡ 6H2O |
| 8.DD.35 | Gutsevichite | Al3(PO4)2(OH)3 ¡ 8H2O |
| 8.DD.40 | Laubmannite (of Moore) | (Fe3+,Fe2+,M)8+x(OH,H2O)9(H2O)2(PO4)5, M = Fe3+, Cu2+ or other metal cation, x ~ 0.1. |
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.
Internet Links for Ernstite
mindat.org URL:
https://www.mindat.org/min-1404.html
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References for Ernstite
Reference List:
Localities for Ernstite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
â - 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 | |
| ÄernĂ˝ et al. (2011) |
Australia | |
| Mineralogical Society of America - ... |
Brazil | |
| Mineralogical Record (2001) |
| Richard Dale Collection | |
| Wilson (1990) | |
| Taquaral |
Canada | |
| Robinson et al. (1992) |
| Robinson et al. (1992) | |
Finland | |
| SandstrĂśm et al. (2009) |
Germany | |
| Harald G. Dill and Radek Skoda (2015) |
Namibia (TL) | |
| [NJMM (1970) +1 other reference |
Spain | |
| Merino et al. (2013) |
USA | |
| |
| Mineral Webzine |
| Loomis (2011) |
Quick NavTopAbout ErnstiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
St John's Quarry, Kapunda, North Mt Lofty Ranges, Mt Lofty Ranges, South Australia, Australia