Robertsite
A valid IMA mineral species
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About Robertsite
Willard "Bill" Lincoln Roberts
Formula:
Ca2Mn3+3(PO4)3O2 · 3H2O
Colour:
Red, red-brown, deep red, bronzy brown, black
Lustre:
Waxy, Greasy, Pearly
Hardness:
3½
Specific Gravity:
3.13
Crystal System:
Monoclinic
Member of:
Name:
Named in 1974 by Paul Brian Moore and Jun Ito in honor of Willard "Bill" Lincoln Roberts [February 12, 1923 Epworth, Iowa, USA - March 23, 1987 Rapid City, South Dakota, USA], professor of mineralogy and curator of the South Dakota School of Mines mineral museum. Bill was strongly influenced by the phosphate mineral bearing granite pegmatites of the nearby Black Hill and collaborated with many mineralogists, including Mary Mrose, Paul Moore, and Jun Ito and through this collaboration about 15-20 phosphates minerals were described by various authors. Bill was senior author of both the Mineralogy of the Black Hills and the Encyclopedia of Minerals (first edition).
Dimorph of:
Isostructural with:
Brown to dark brown coatings, usually fine-grained, but sometimes crystallized with densely packed pseudohexagonal platy, columnar, or fibrous crystals.
Much more common than its dimorph pararobertsite.
Much more common than its dimorph pararobertsite.
Unique Identifiers
Mindat ID:
3431
Long-form identifier:
mindat:1:1:3431:5
GUID
(UUID V4):
(UUID V4):
99689eba-c851-472e-8f7a-c352c7224fb3
IMA Classification of Robertsite
Approved
IMA Formula:
Ca2Mn3+3O2(PO4)3 · 3H2O
Approval year:
1973
First published:
1974
Type description reference:
Classification of Robertsite
8.DH.30
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
H : With large and medium-sized cations, (OH, etc.):RO4 < 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
H : With large and medium-sized cations, (OH, etc.):RO4 < 1:1
42.8.4.2
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
8 : (AB)5(XO4)3Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
8 : (AB)5(XO4)3Zq·xH2O
19.12.6
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 |
|---|---|---|
| Rbt | IMAâCNMNC | Warr, L.N. (2021). IMAâCNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Robertsite
Waxy, Greasy, Pearly
Transparency:
Translucent
Comment:
Bright relections on basal sections
Colour:
Red, red-brown, deep red, bronzy brown, black
Streak:
Red-brown
Hardness:
3½ on Mohs scale
Tenacity:
Waxy
Cleavage:
Very Good
{100}
{100}
Fracture:
Micaceous
Density:
3.13 g/cm3 (Measured) 3.05 g/cm3 (Calculated)
Optical Data of Robertsite
Type:
Biaxial (-)
RI values:
nα = 1.775 nβ = 1.820 nγ = 1.820
2V:
Measured: 8°
Birefringence:
0.045
Max Birefringence:
δ = 0.045
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:
Very High
Dispersion:
relatively weak
Optical Extinction:
X ~ â„ {100}
Pleochroism:
Strong
Comments:
X pale red to pink Y,Z deep red brown
Chemistry of Robertsite
Mindat Formula:
Ca2Mn3+3(PO4)3O2 · 3H2O
Crystallography of Robertsite
Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Setting:
Bb
Cell Parameters:
a = 17.3400(9) Å, b = 19.4464(10) Å, c = 11.2787(6) Å
β = 96.634(3)°
β = 96.634(3)°
Ratio:
a:b:c = 0.892 : 1 : 0.58
Unit Cell V:
3777.7 Ă
Âł
Z:
12
Morphology:
Frequently earthy in coatings. Not rarely scaly or in densely packed crystals in subparallel groupings. Crystals frequently show corrugations and deep striations or notches.
Twinning:
Multiple rotation twins (Ï/3) perpendicular to {100}
Comment:
A non-standard cell chosen, cfr Andrade et al. (2012)
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 0019365 | Robertsite | Andrade M B, Morrison S M, Di Domizio A J, Feinglos M N, Downs R T (2012) Robertsite, Ca2MnIII3O2(PO4)*3H2O Acta Crystallographica E68 i74-i75 |  | 2012 | Tip Top mine, Custer County, South Dakota, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.63 Ă | (100) |
| 5.61 Ă | (50) |
| 3.27 Ă | (40) |
| 2.88 Ă | (30) |
| 2.75 Ă | (60) |
| 2.59 Ă | (40) |
| 2.16 Ă | (30) |
| 1.623 Ă | (50) |
Comments:
26-1067
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 21 : Chemically precipitated carbonate, phosphate, iron formations | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 48 : Soil leaching zone minerals | <0.6 |
| 52 : Guano- and urine-derived minerals | <0.4 |
| 53 : Other minerals with taphonomic origins | <0.4 |
Type Occurrence of Robertsite
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 127151.
Geological Setting of Type Material:
Late stage mineralization in granite pegmatites.
Associated Minerals at Type Locality:
Reference:
Moore, P.B., Ito, J. (1974) Jahnsite, segelerite, and robertsite, three new transition metal phosphates species: American Mineralogist: 59: 48-60.
Synonyms of Robertsite
Other Language Names for Robertsite
German:Robertsit
Spanish:Robertsita
Relationship of Robertsite to other Species
Member of:
Other Members of this group:
| Arseniosiderite | Ca2Fe3+3(AsO4)3O2 · 3H2O | Mon. 2/m : B2/b |
| Kolfanite | Ca2Fe3+3O2(AsO4)3 · 2H2O | Mon. |
| Mitridatite | Ca2Fe3+3(PO4)3O2 · 3H2O | Mon. 2/m : B2/b |
Forms a series with:
Common Associates
Associated Minerals Based on Photo Data:
| 30 photos of Robertsite associated with Montgomeryite | Ca4MgAl4(PO4)6(OH)4 · 12H2O |
| 20 photos of Robertsite associated with Whitlockite | Ca9Mg(PO4)6(PO3OH) |
| 13 photos of Robertsite associated with Collinsite | Ca2Mg(PO4)2 · 2H2O |
| 12 photos of Robertsite associated with Leucophosphite | KFe3+2(PO4)2(OH) · 2H2O |
| 12 photos of Robertsite associated with Rockbridgeite | Fe2+Fe3+4(PO4)3(OH)5 |
| 8 photos of Robertsite associated with Hureaulite | Mn2+5(PO3OH)2(PO4)2 · 4H2O |
| 7 photos of Robertsite associated with Bermanite | Mn2+Mn3+2(PO4)2(OH)2 · 4H2O |
| 7 photos of Robertsite associated with Englishite | K3Na2Ca10Al15(PO4)21(OH)7 · 26H2O |
| 7 photos of Robertsite associated with Phosphosiderite | FePO4 · 2H2O |
| 6 photos of Robertsite associated with Strengite | FePO4 · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 8.DH. | Ferroberaunite | Fe2+Fe3+5(PO4)4(OH)5 · 6H2O |
| 8.DH. | Rowleyite | [Na(NH4,K)9Cl4][V5+,4+2(P,As)O8]6 · n[H2O,Na,NH4,K,Cl] |
| 8.DH. | Ammoniotinsleyite | (NH4)Al2(PO4)2(OH) · 2H2O |
| 8.DH. | Thebaite-(NH4) | (NH4)3Al(C2O4)(PO3OH)2(H2O) |
| 8.DH. | Dendoraite-(NH4) | (NH4)2NaAl(C2O4)(PO3OH)2(H2O)2 |
| 8.DH. | Whiteite-(MnMnMn) | Mn2+Mn2+Mn2+2Al2(PO4)4(OH)2 · 8H2O |
| 8.DH. | Whiteite-(CaMnFe) | CaMnFe2Al2(PO4)4(OH)2 · 8H2O |
| 8.DH. | Hochleitnerite | Mn2Ti3(PO4)4O2(H2O)2 · 14H2O |
| 8.DH. | Regerite | KFe6(PO4)4(OH)7(H2O)6 · 4H2O |
| 8.DH.05 | Minyulite | KAl2(PO4)2F · 4H2O |
| 8.DH.10 | Leucophosphite | KFe3+2(PO4)2(OH) · 2H2O |
| 8.DH.10 | Spheniscidite | (NH4,K)(Fe3+,Al)2(PO4)2(OH) · 2H2O |
| 8.DH.10 | Tinsleyite | KAl2(PO4)2(OH) · 2H2O |
| 8.DH.15 | Jahnsite-(CaMnFe) | {Ca}{Mn2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(CaMnMg) | {Ca}{Mn2+}{(Mg,Fe2+)2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(CaMnMn) | {Ca}{Mn2+}{Mn2+2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Keckite | CaMn2+(Fe3+Mn2+)Fe3+2(PO4)4(OH)3 · 7H2O |
| 8.DH.15 | Rittmannite | {(Mn2+,Ca)}{Mn2+}{(Fe2+,Mn2+,Mg)2}{(Al,Fe3+)2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Whiteite-(CaFeMg) | {Ca}{(Fe2+,Mn2+)}{Mg2}{Al2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Whiteite-(CaMnMg) | {Ca}{Mn2+}{Mg2}{Al2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Whiteite-(MnFeMg) | {(Mn2+,Ca)}{(Fe2+,Mn2+)}{Mg2}{Al2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(MnMnMn) | {Mn2+}{Mn2+}{Mn2+2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Kaluginite | (Mn2+,Ca)MgFe3+(PO4)2(OH) · 4H2O |
| 8.DH.15 | Jahnsite-(CaFeFe) | {Ca}{Fe2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(NaFeMg) | NaFe3+Mg2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(NaMnMg) | {(Na,Ca)}{(Mn2+,Fe3+)}{(Mg,Fe3+)2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(CaMgMg) | {Ca}{Mg}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Whiteite-(CaMnMn) | {Ca}{Mn2+}{Mn2}{Al2}(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Whiteite-(MnMnMg) | MnMnMg2Al2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(MnMnMg) | Mn2+Mn2+Mg2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(CaFeMg) | CaFe2+Mg2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(MnMnFe) | Mn2+Mn2+Fe2+2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Whiteite-(CaMgMg) | CaMg3Al2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(MnMnZn) | Mn2+Mn2+Zn2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(NaMnMn) | NaMn2+(Mn2+Fe3+)Σ2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.15 | Jahnsite-(CaMnZn) | CaMn2+Zn2Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.20 | Lun'okite | (Mn,Ca)(Mg,Fe,Mn)Al(PO4)2OH · 4H2O |
| 8.DH.20 | Manganosegelerite | (Mn2+,Ca)(Mn2+,Fe2+,Mg)Fe3+(PO4)2(OH) · 4H2O |
| 8.DH.20 | Overite | CaMgAl(PO4)2(OH) · 4H2O |
| 8.DH.20 | Segelerite | Ca2 Mg2 Fe3+2(PO4)4(OH)2 · 8H2O |
| 8.DH.20 | Wilhelmvierlingite | CaMnFe3+(PO4)2(OH) · 2H2O |
| 8.DH.20 | Juonniite | CaMgSc(PO4)2(OH) · 4H2O |
| 8.DH.25 | Calcioferrite | Ca2Fe3+2(PO4)3(OH) · 7H2O |
| 8.DH.25 | Kingsmountite | Ca3MnFeAl4(PO4)6(OH)4 · 12H2O |
| 8.DH.25 | Montgomeryite | Ca4MgAl4(PO4)6(OH)4 · 12H2O |
| 8.DH.25 | Zodacite | Ca4Mn2+Fe3+4(PO4)6(OH)4 · 12H2O |
| 8.DH.25 | Fanfaniite | Ca4MnAl4(PO4)6(OH)4 · 12H2O |
| 8.DH.30 | Arseniosiderite | Ca2Fe3+3(AsO4)3O2 · 3H2O |
| 8.DH.30 | Kolfanite | Ca2Fe3+3O2(AsO4)3 · 2H2O |
| 8.DH.30 | Mitridatite | Ca2Fe3+3(PO4)3O2 · 3H2O |
| 8.DH.30 | Pararobertsite | Ca2Mn3+3(PO4)3O2 · 3H2O |
| 8.DH.30 | Sailaufite | (Ca,Na,â»)2Mn3+3(AsO4)2(CO3)O2 · 3H2O |
| 8.DH.35 | Mantienneite | KMg2Al2Ti(PO4)4(OH)3 · 15H2O |
| 8.DH.35 | Paulkerrite | K(Mg,Mn2+)2(Fe3+,Al,Ti,Mg)2Ti(PO4)4(OH)3 · 15H2O |
| 8.DH.35 | Benyacarite | (H2O)2Mn2Ti2Fe3+(PO4)4(OF)(H2O)10 · 4H2O |
| 8.DH.35 | Hydroxylbenyacarite | (H2O)2Mn2(Ti2Fe)(PO4)4[O(OH)](H2O)10 · 4H2O |
| 8.DH.35 | Macraeite | K(H2O)Mn2(Fe2Ti)(PO4)4[O(OH)](H2O)10 · 4H2O |
| 8.DH.35 | Sperlingite | (H2O)K(Mn2+Fe3+)(Al2Ti)(PO4)4[O(OH)] [(H2O)9(OH)] · 4H2O |
| 8.DH.40 | Xanthoxenite | Ca4Fe3+2(PO4)4(OH)2 · 3H2O |
| 8.DH.45 | Mahnertite | NaCu3(AsO4)2Cl · 5H2O |
| 8.DH.50 | Andyrobertsite | KCdCu5(AsO4)4(H2AsO4) · 2H2O |
| 8.DH.50 | Calcioandyrobertsite | KCaCu5(AsO4)4(H2AsO4) · 2H2O |
| 8.DH.55 | Englishite | K3Na2Ca10Al15(PO4)21(OH)7 · 26H2O |
| 8.DH.60 | Bouazzerite | Bi6(Mg,Co)11Fe3+14(AsO4)18(OH)4O12 · 86H2O |
| 8.DH.65 | Galliskiite | Ca4Al2(PO4)2F8 · 5H2O |
| 8.DH.70 | Joteite | Ca2CuAl(AsO4)[AsO3(OH)]2(OH)2 · 5H2O |
| 8.DH.75 | Kampelite | Ba6Mg3Sc8(PO4)12(OH)6 · 7H2O |
| 8.DH.80 | Kapundaite | NaCaFe4(PO4)4(OH)3 · 5H2O |
| 8.DH.85 | Vaniniite | Ca2Mn2+3Mn3+2O2(AsO4)4 · 2H2O |
Fluorescence of Robertsite
nonfluorescent
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 Robertsite
mindat.org URL:
https://www.mindat.org/min-3431.html
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References for Robertsite
Reference List:
Moore, Paul Brian, Ito, J. (1974) I. Jahnsite, segelerite, and robertsite, three new transition metal phosphate species. II. Redefinition of overite, an isotype of segelerite. III. Isotypy of robertsite, mitridatite, and arseniosiderite. American Mineralogist, 59 (1-2) 48-59
Localities for Robertsite
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 | |
| Biglia et al. (2021) |
| Roda-Robles et al. (2012) |
Australia | |
| Francis (2010) |
| Francis et al. (self published) |
| Jacobson et al. (2007) |
Brazil | |
| Sergio Varvello collection |
| Baijot et al. (2014) +1 other reference | |
| Sergio Varvello collection | |
| Roberto Bosi collection |
| Sergio Varvello collection |
Ethiopia | |
| American Mineralogist |
Europe | |
| Berbain et al. (2012) | |
France | |
| Boisson et al. (2000) |
| Berbain et al. (2012) |
Germany | |
| WeiĂ (1990) |
| Mineralogical Magazine 1988 52 : 505-508 +2 other references |
| Dill et al. (2008) | |
| Bender et al. (1994) |
Italy | |
| Baldoni et al. (2013) +2 other references |
| Audra et al. (2019) |
Morocco | |
| Favreau (2012) |
| Favreau (2012) |
Namibia | |
| von Bezing (2007) |
| Keller (1974) | |
| Förch (1998) |
| Bezing et al. (2007) |
| von Bezing (2007) |
| von Bezing (2007) |
| von Bezing (2007) | |
Poland | |
| Pieczka et al. (2015) |
| Pieczka et al. (2015) +1 other reference |
Portugal | |
| Self-find by Nuno Afonso +1 other reference |
| |
Romania | |
| Mineralogical Record 7:139-140 |
Spain | |
| |
Thailand | |
| Van Kauwenbergh et al. (1988) |
USA | |
| Jahns (1952) +1 other reference |
| London |
| Fisher (2002) |
| Falster et al. (2019) |
| www.webmineral.com (2000) +1 other reference |
| Robert Whitmore collection |
| |
| Van Kauwenbergh et al. (1988) |
| Moore et al. (1974) |
| Van Kauwenbergh et al. (1988) |
| Smith et al. (2000) |
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Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA