Ajoite
A valid IMA mineral species - grandfathered
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About Ajoite
Ajo Mine (1916 or earlier)
New Cornelia Mine, Ajo, Little Ajo Mountains, Ajo Mining District, Pima County, Arizona, USA
New Cornelia Mine, Ajo, Little Ajo Mountains, Ajo Mining District, Pima County, Arizona, USA
Formula:
(K,Na)Cu7AlSi9O24(OH)6 · 3H2O
Colour:
Bluish green
Specific Gravity:
2.96
Crystal System:
Triclinic
Name:
Named after the type locality, the New Cornelia mine in Ajo, Arizona, USA (http://www.mindat.org/loc-3370.html)
See also Best Minerals article on ajoite: Currier, R., Revheim O. (2016): Ajoite. revision 2.1 Mindat Best Minerals Project, article "mesg-66-124530":
http://www.mindat.org/mesg-66-124530.html
http://www.mindat.org/mesg-66-124530.html
Unique Identifiers
Mindat ID:
66
Long-form identifier:
mindat:1:1:66:2
Similar Names
IMA Classification of Ajoite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
K3Cu2+20Al3Si29O76(OH)16·8H2O
First published:
1958
Classification of Ajoite
9.EA.70
9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings
9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings
78.5.1.1
78 : Unclassified Silicates
5 :
78 : Unclassified Silicates
5 :
16.5.6
16 : Silicates Containing Aluminum and other Metals
5 : Aluminosilicates of Cs, NH4 and Cu
16 : Silicates Containing Aluminum and other Metals
5 : Aluminosilicates of Cs, NH4 and Cu
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 |
|---|---|---|
| Aj | 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 Ajoite
Transparency:
Translucent
Colour:
Bluish green
Streak:
Greenish white
Cleavage:
Perfect
on {010}
on {010}
Density:
2.96 g/cm3 (Measured) 2.951 g/cm3 (Calculated)
Optical Data of Ajoite
Type:
Biaxial (+)
RI values:
nα = 1.550(1) nβ = 1.583(1) nγ = 1.641(1)
2V:
Measured: 80° (1), Calculated: 76.4°
Max. Birefringence:
δ = 0.091
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:
r < v strong
Pleochroism:
Visible
Comments:
X= very light bluish green
Y=Z= brilliant bluish green
Y=Z= brilliant bluish green
Chemistry of Ajoite
Mindat Formula:
(K,Na)Cu7AlSi9O24(OH)6 · 3H2O
Element Weights:
Common Impurities:
Fe,Mn,Ca
Crystallography of Ajoite
Crystal System:
Triclinic
Cell Parameters:
a = 13.634(5) Å, b = 13.687(7) Å, c = 14.522(7) Å
α = 110.83(1)°, β = 107.21(1)°, γ = 105.68(1)°
α = 110.83(1)°, β = 107.21(1)°, γ = 105.68(1)°
Ratio:
a:b:c = 0.996 : 1 : 1.061
Unit Cell V:
2,195.04 ų (Calculated from Unit Cell)
Z:
3
Morphology:
As sprays of bladed prismatic crystals, to 0.4 mm; commonly fibrous.
From New Cornelia mine {010} is the most prominent form and {100} and {110} are much less prominent but always present. The termination on c may be either {001} or {203} or both.
From New Cornelia mine {010} is the most prominent form and {100} and {110} are much less prominent but always present. The termination on c may be either {001} or {203} or both.
Comment:
Cell parameters from Pluth and Smith (2002)
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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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) |
|---|---|---|---|---|---|---|---|
| 0015331 | Ajoite | Pluth J J, Smith J V (2002) Arizona porphyry copper/hydrothermal deposits II: Crystal structure of ajoite, (K+Na)3Cu20Al3Si29O76(OH)16*~8H2O Proceedings of the National Academy of Sciences 99 11002-11005 | 2002 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 12.25 Å | (100) |
| 4.08 Å | (10) |
| 3.381 Å | (8) |
| 3.061 Å | (10) |
| 2.832 Å | (8) |
| 2.455 Å | (12) |
| 2.258 Å | (8) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Geological Setting:
In oxidised copper-rich base-metal deposits.
Type Occurrence of Ajoite
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 113220.
Associated Minerals at Type Locality:
Other Language Names for Ajoite
Common Associates
Associations Based on Photo Data:
| 269 photos of Ajoite associated with Quartz | SiO2 |
| 49 photos of Ajoite associated with Shattuckite | Cu5(Si2O6)2(OH)2 |
| 37 photos of Ajoite associated with Hematite | Fe2O3 |
| 37 photos of Ajoite associated with Papagoite | CaCu[H3AlSi2O9] |
| 32 photos of Ajoite associated with Native Copper | Cu |
| 7 photos of Ajoite associated with Pyrite | FeS2 |
| 7 photos of Ajoite associated with Kaolinite | Al2(Si2O5)(OH)4 |
| 7 photos of Ajoite associated with Cuprorivaite | CaCuSi4O10 |
| 6 photos of Ajoite associated with Olivenite | Cu2(AsO4)(OH) |
| 6 photos of Ajoite associated with Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
Related Minerals - Strunz-mindat Grouping
| 9.EA. | Hydroxymcglassonite-(K) | KSr4Si8O20(OH) · 8H2O |
| 9.EA. | Miyawakiite-(Y) | ◻Y4Fe2(Si8O20)(CO3)4(H2O)3 |
| 9.EA. | Bussyite-(Y) | (Y,REE,Ca)3(Na,Ca)6MnSi9Be5(O,OH,F)34 |
| 9.EA. | Fluorapophyllite-(NH4) | NH4Ca4(Si8O20)F · 8H2O |
| 9.EA.05 | Gillespite | BaFe2+Si4O10 |
| 9.EA.05 | Cuprorivaite | CaCuSi4O10 |
| 9.EA.05 | Wesselsite | SrCuSi4O10 |
| 9.EA.05 | Effenbergerite | BaCuSi4O10 |
| 9.EA.07 | Fluorapophyllite-(Cs) | CsCa4(Si8O20)F · 8H2O |
| 9.EA.10 | Ekanite | Ca2ThSi8O20 |
| 9.EA.15 | Fluorapophyllite-(Na) | NaCa4(Si8O20)F · 8H2O |
| 9.EA.15 | Fluorapophyllite-(K) | KCa4(Si8O20)(F,OH) · 8H2O |
| 9.EA.15 | Hydroxyapophyllite-(K) | KCa4(Si8O20)(OH,F) · 8H2O |
| 9.EA.20 | Magadiite | Na2Si14O29 · 11H2O |
| 9.EA.25 | Dalyite | K2ZrSi6O15 |
| 9.EA.25 | Davanite | K2TiSi6O15 |
| 9.EA.30 | Sazhinite-(La) | Na3La[Si6O15] · 2H2O |
| 9.EA.30 | Sazhinite-(Ce) | Na3CeSi6O15 · 2H2O |
| 9.EA.35 | Armstrongite | CaZr[Si6O15] · 3H2O |
| 9.EA.40 | Okenite | Ca10Si18O46 · 18H2O |
| 9.EA.45 | Perettiite-(Y) | Y2Mn4FeSi2B8O24 |
| 9.EA.45 | Nekoite | Ca3Si6O15 · 7H2O |
| 9.EA.45 | Badakhshanite-(Y) | Y2Mn4Al(Si2B7BeO24) |
| 9.EA.47 | Shlykovite | KCa[Si4O9(OH)] · 3H2O |
| 9.EA.50 | Diegogattaite | Na2CaCu2Si8O20 · H2O |
| 9.EA.50 | Cavansite | Ca(VO)Si4O10 · 4H2O |
| 9.EA.52 | Yangite | PbMnSi3O8 · H2O |
| 9.EA.55 | Pentagonite | Ca(VO)Si4O10 · 4H2O |
| 9.EA.60 | Penkvilksite | Na4Ti2Si8O22 · 4H2O |
| 9.EA.60 | Tumchaite | Na2Zr(Si4O11) · 2H2O |
| 9.EA.65 | Nabesite | Na2BeSi4O10 · 4H2O |
| 9.EA.75 | Zeravshanite | Na2Cs4Zr3[Si18O45]*2H2O |
| 9.EA.80 | Bussyite-(Ce) | (Ce,REE)3(Na,H2O)6MnSi9Be5(O,OH)30F4 |
| 9.EA.85 | Plumbophyllite | Pb2Si4O10 · H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 2.9989% | 930 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
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 Ajoite
mindat.org URL:
https://www.mindat.org/min-66.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Ajoite
Reference List:
Schaller, W. T., Vlisidis, A. C. (1958) Ajoite, a new hydrous aluminum copper silicate. American Mineralogist, 43 (11-12) 1107-1111
Kato, Toshio, Miúra, Yasunori (1976) Cell dimensions of ajoite. Mineralogical Journal, 8 (4) 234-239 doi:10.2465/minerj.8.234
Frost, Ray L., Xi, Yunfei (2012) Vibrational spectroscopic study of the copper silicate mineral ajoite (K,Na)Cu7AlSi9O24(OH)6·3H2O. Journal of Molecular Structure, 1018. 72-77 doi:10.1016/j.molstruc.2011.10.056
Localities for Ajoite
Showing 20 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.
Austria | |
| G.Blaß |
| Niedermayr (1996) |
Germany | |
| Schnorrer-Köhler (1990) |
Japan | |
| Numao et al (2005) |
Mexico | |
| Megaw (2023) |
Namibia | |
| Niedermayr (2001) |
Romania | |
| minerals-of-the-carpathians.eu (2008) |
| Hîrtopanu (1997) +1 other reference |
South Africa | |
| Cairncross (1991) +2 other references |
| Moore et al. (2016) | |
| Cairncross et al. (1995) | |
Spain | |
| Joan Abella i Creus (Joanabellacreus@gmail.com) |
UK | |
| www.mindat.org (n.d.) |
USA | |
| Williams (1968) +1 other reference |
| Williams (1968) +2 other references |
| Sun (1961) +1 other reference |
| Schaller et al. (1958) +7 other references |
| Lalith Aditya Senthil Kumar Collection |
| Thorne (n.d.) |
| Mr. Joe Ruiz. |
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Messina Mine, Musina, Musina Local Municipality, Vhembe District Municipality, Limpopo, South Africa