Millisite
A valid IMA mineral species - grandfathered
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About Millisite
Formula:
(Na,K)CaAl6(PO4)4(OH)9 · 3H2O
Colour:
White, light gray; colourless in transmitted light.
Hardness:
5½
Specific Gravity:
2.83
Crystal System:
Tetragonal
Member of:
Name:
Named in 1942 by Esper Signius Larsen III in honor of Mr. F. T. Millis of Lehi, Utah County, Utah, who had discovered and was an early miner of the variscite locality.
Unique Identifiers
Mindat ID:
2712
Long-form identifier:
mindat:1:1:2712:6
Similar Names
IMA Classification of Millisite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
NaCaAl6(PO4)4(OH)9·3H2O
First published:
1930
Classification of Millisite
8.DL.10
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
42.7.9.1
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
19.8.20
19 : Phosphates
8 : Phosphates of Al and other metals
19 : Phosphates
8 : Phosphates of Al and other metals
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 |
|---|---|---|
| Mill | 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 Millisite
Colour:
White, light gray; colourless in transmitted light.
Hardness:
5½ on Mohs scale
Density:
2.83 g/cm3 (Measured) 2.87 g/cm3 (Calculated)
Optical Data of Millisite
Type:
Biaxial (+)
RI values:
nα = 1.584 nβ = 1.598 nγ = 1.602
Max. Birefringence:
δ = 0.018
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.
No measured or calculated 2V is on file for this mineral, so the value used here (124°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
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.
No measured or calculated 2V is on file for this mineral, so the value used here (124°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
small
Chemistry of Millisite
Mindat Formula:
(Na,K)CaAl6(PO4)4(OH)9 · 3H2O
Element Weights:
Crystallography of Millisite
Crystal System:
Tetragonal
Cell Parameters:
a = 7.00 Å, c = 18.99 Å
Ratio:
a:c = 1 : 2.713
Unit Cell V:
930.51 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Chalcedonic crusts or spherules with a fine-fibrous structure.
Comment:
Other values reported: 7.00, 19.07 (Owens et al., 1960).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.6 Å | (40) |
| 4.84 Å | (100b) |
| 3.93 Å | (30) |
| 3.48 Å | (30) |
| 3.09 Å | (60b) |
| 2.98 Å | (80b) |
| 2.81 Å | (80b) |
Comments:
Similar to wardite.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 21 : Chemically precipitated carbonate, phosphate, iron formations | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| 47g : [Halogen-bearing surface weathering minerals] |
Geological Setting:
Phosphatic laterite; weathered phosphorite.
Type Occurrence of Millisite
Associated Minerals at Type Locality:
Synonyms of Millisite
Other Language Names for Millisite
Relationship of Millisite to other Species
Member of:
Other Members of Wardite Group:
| Cyrilovite | NaFe3+3(PO4)2(OH)4 · 2H2O | Tet. 422 : P41212 |
| Fluorowardite | NaAl3(PO4)2F2(OH)2(H2O)2 | Tet. 422 : P41212 |
| Wardite | NaAl3(PO4)2(OH)4 · 2H2O | Tet. 422 : P41212 |
Common Associates
Associations Based on Photo Data:
| 46 photos of Millisite associated with Crandallite | CaAl3(PO4)(PO3OH)(OH)6 |
| 42 photos of Millisite associated with Wardite | NaAl3(PO4)2(OH)4 · 2H2O |
| 24 photos of Millisite associated with Variscite | AlPO4 · 2H2O |
| 10 photos of Millisite associated with Fluorapatite | Ca5(PO4)3F |
| 9 photos of Millisite associated with Montgomeryite | Ca4MgAl4(PO4)6(OH)4 · 12H2O |
| 8 photos of Millisite associated with Gordonite | MgAl2(PO4)2(OH)2 · 8H2O |
| 4 photos of Millisite associated with 'Carbonate-rich Apatite' | Ca5(PO4)3(Cl/F/OH) |
| 3 photos of Millisite associated with 'Chalcedony' | SiO2 |
| 2 photos of Millisite associated with Quartz | SiO2 |
| 2 photos of Millisite associated with Hematite | Fe2O3 |
Related Minerals - Strunz-mindat Grouping
| 8.DL.05 | Foggite | CaAl(PO4)(OH)2 · H2O |
| 8.DL.10 | Fluorowardite | NaAl3(PO4)2F2(OH)2(H2O)2 |
| 8.DL.10 | Wardite | NaAl3(PO4)2(OH)4 · 2H2O |
| 8.DL.10 | Cyrilovite | NaFe3+3(PO4)2(OH)4 · 2H2O |
| 8.DL.15 | Petersite-(Ce) | CeCu6(PO4)3(OH)6 · 3H2O |
| 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 | Petersite-(Y) | YCu6(PO4)3(OH)6 · 3H2O |
| 8.DL.15 | Zálesíite | CaCu6(AsO4)2(AsO3OH)(OH)6 · 3H2O |
| 8.DL.15 | Mixite | BiCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Petersite-(La) | LaCu6(PO4)3(OH)6 · 3H2O |
| 8.DL.15 | Goudeyite | AlCu6(AsO4)3(OH)6 · 3H2O |
| 8.DL.15 | Calciopetersite | CaCu6(PO4)2(PO3OH)(OH)6 · 3H2O |
| 8.DL.15 | Plumboagardite | PbCu6(AsO4)2(AsO3OH)(OH)6 · 3H2O |
| 8.DL.20 | Dugganite | Pb3Zn3(AsO4)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.20 | Cheremnykhite | Pb3Zn3(VO4)2(TeO6) |
| 8.DL.20 | Kuksite | Pb3Zn3(PO4)2(TeO6) |
| 8.DL.25 | Angastonite | CaMgAl2(PO4)2(OH)4 · 7H2O |
| 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 Millisite
mindat.org URL:
https://www.mindat.org/min-2712.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Millisite
Reference List:
Larsen, Esper S., Shannon, Earl V. (1930) The minerals of the phosphate nodules from near Fairfield, Utah. American Mineralogist, 15 (8) 307-337
Larsen, Esper S., 3d, (1942) The mineralogy and paragenesis of the variscite nodules from near Fairfield, Utah, Part 1. American Mineralogist, 27 (4) 281-300 p.294
Fanfani, L., Nunzi, A., Zanazzi, P. F. (1970) The crystal structure of wardite. Mineralogical Magazine, 37 (289) 598-605 doi:10.1180/minmag.1970.037.289.10
Localities for Millisite
Showing 17 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.
Australia | |
| Doak et al. (1965) +1 other reference | |
| Francis (2010) |
| Pilkington et al. (1979) |
| Nickel (2008) |
Austria | |
| Collection of NHM +2 other references |
| Pichler (2009) |
Portugal | |
| Alves (n.d.) |
Rwanda | |
| Anthony et al. (2016) |
Senegal | |
| www.uoguelph.ca (2003) |
Sweden | |
| Hansen et al. (1994) |
USA | |
| Denicourt +1 other reference |
| Altschuler et al. (1956) +1 other reference | |
| Marc V. Hurst (2012) |
| Silver Coin Mine. Compact Disc. Paul ... |
| Bullock (1981) |
| Palache et al. (1951) +1 other reference |
| Rocks & Minerals (1970) +1 other reference |
Quick NavTopAbout MillisiteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Iron Monarch Main Pit, Iron Knob, Pastoral Unincorporated Area, South Australia, Australia