Angastonite
A valid IMA mineral species
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About Angastonite
Formula:
CaMgAl2(PO4)2(OH)4 · 7H2O
Colour:
Snow white
Lustre:
Pearly
Hardness:
2
Specific Gravity:
1.57
Crystal System:
Amorphous
Name:
The mineral is named for the town of Angaston, which is named after George Fife Angas (1789–1879), businessman and Member of Parliament of South Australia, who settled in the area in the 1850s.
A reinvestigation of the type angastonite specimen showed that the published powder X-ray diffraction pattern for the mineral corresponds to a mixture of crystalline phases plus an amorphous phase; the latter was redefined as angastonite (Grey et al., 2022). One of the crystalline phases is elliottite.
Unique Identifiers
Mindat ID:
35972
Long-form identifier:
mindat:1:1:35972:6
GUID
(UUID V4):
(UUID V4):
66ef4a37-af93-4973-b6e9-29a2db49fd73
IMA Classification of Angastonite
Approved
IMA status notes:
Redefined by the IMA
Approval year:
2008
Approval history:
2021: Redefinition as an amorphous mineral (IMA 21-J proposal, Grey et al., 2022).
Classification of Angastonite
8.DL.25
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
L : With large and medium-sized cations, (OH, etc.):RO4 = 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
L : With large and medium-sized cations, (OH, etc.):RO4 = 2:1
42.7.22.
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
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 |
|---|---|---|
| Ags | 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 Angastonite
Pearly
Colour:
Snow white
Streak:
White
Hardness:
2 on Mohs scale
Hardness Data:
Estimated
Density:
1.57(2) g/cm3 (Measured)
Comment:
Originally given as 2.47 (meas.), 2.332 (calc.).
Optical Data of Angastonite
Type:
Isotropic
RI values:
n = 1.33 - 1.40
Birefringence:
Isotropic minerals have no birefringence
Surface Relief:
Moderate
Pleochroism:
Non-pleochroic
Comments:
Originally thought to be biaxial (+), with alpha 1.566, beta 1.572, gamma 1.584, 2V(meas.) 70°, 2V(calc.) 71°.
Weak pleochroism, with X = colourless, Y = colourless to pale yellow, Z = colourless.
Weak pleochroism, with X = colourless, Y = colourless to pale yellow, Z = colourless.
Chemistry of Angastonite
Mindat Formula:
CaMgAl2(PO4)2(OH)4 · 7H2O
Crystallography of Angastonite
Crystal System:
Amorphous
Morphology:
Refers to original erroneous description: Platy crystals with the forms {010} (prominent), {101}, {101} and {100} (rare), and also occurs as replacements of an unknown pre-existing mineral.
Comment:
Formerly thought to be crystalline, triclinic, a = 13.303(1), b = 27.020(2), c = 6.1070(7), α = 89.64(1), β = 83.44(1), γ = 80.444(8); now proven to be actually amorphous (Grey et al., 2022).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| - Ã… | () |
Comments:
"Broad humps centered at 2θ ≈ 25 and 2θ ≈ 35 (CoKα)" (Grey et al., 2022).
Originally given values: 13.38 (100), 11.05 (25), 5.73 (23), 8.01 (21).
Originally given values: 13.38 (100), 11.05 (25), 5.73 (23), 8.01 (21).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] |
Type Occurrence of Angastonite
General Appearance of Type Material:
White
Place of Conservation of Type Material:
Museum Victoria
Associated Minerals at Type Locality:
Synonyms of Angastonite
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.DL.05 | Foggite | CaAl(PO4)(OH)2 · H2O |
| 8.DL.10 | Cyrilovite | NaFe3+3(PO4)2(OH)4 · 2H2O |
| 8.DL.10 | Millisite | (Na,K)CaAl6(PO4)4(OH)9 · 3H2O |
| 8.DL.10 | Wardite | NaAl3(PO4)2(OH)4 · 2H2O |
| 8.DL.10 | Fluorowardite | NaAl3(PO4)2F2(OH)2(H2O)2 |
| 8.DL.15 | Agardite-(Nd) | NdCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Agardite-(Y) | YCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Agardite-(Ce) | CeCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Agardite-(Dy) | (Dy,La)Cu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Agardite-(La) | LaCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Goudeyite | AlCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Mixite | BiCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Petersite-(Y) | (Y,Ce,Nd)Cu6(PO4)3(OH)6 · 3H2O |
| 8.DL.15 | ZálesÃite | CaCu6(AsO4)2(AsO3OH)(OH)6 · 3H2O |
| 8.DL.15 | Plumboagardite | (Pb,REE,Ca)Cu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Calciopetersite | CaCu6(PO4)2(PO3OH)(OH)6 · 3H2O |
| 8.DL.15 | Petersite-(Ce) | Cu6Ce(PO4)3(OH)6 · 3H2O |
| 8.DL.15 | Petersite-(La) | Cu6La(PO4)3(OH)6 · 3H2O |
| 8.DL.20 | Cheremnykhite | Pb3Zn3(VO4)2(TeO6) |
| 8.DL.20 | Dugganite | Pb3Zn3(AsO4)2(TeO6) |
| 8.DL.20 | Kuksite | Pb3Zn3(PO4)2(TeO6) |
| 8.DL.20 | Wallkilldellite | Ca2Mn2+3(AsO4)2(OH)4 · 9H2O |
| 8.DL.20 | Wallkilldellite-(Fe) | (Ca,Cu)4Fe2+6(AsO4,SiO4)4(OH,O)8 · 18H2O |
| 8.DL.30 | Långbanshyttanite | Pb2Mn2Mg(AsO4)2(OH)4 · 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.
Internet Links for Angastonite
mindat.org URL:
https://www.mindat.org/min-35972.html
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References for Angastonite
Reference List:
Mills, S. J., Groat, L. A., Wilson, S. A., Birch, W. D., Whitfield, P. S., Raudsepp, M. (2008) Angastonite, CaMgAl2(PO4)2(OH)4·7H2O: a new phosphate mineral from Angaston, South Australia. Mineralogical Magazine, 72 (5) 1011-1020 doi:10.1180/minmag.2008.072.5.1011
Localities for Angastonite
ⓘ - 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.
- 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.
Australia (TL) | |
| Mills et al. (2008) +1 other reference |
Quick NavTopAbout AngastoniteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities
Penrice marble quarry, Penrice, Barossa Valley, North Mt Lofty Ranges, Mt Lofty Ranges, South Australia, Australia