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Roymillerite
A valid IMA mineral species
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About Roymillerite
Roy Miller
Formula:
Pb24Mg9(Si10O28)(CO3)10(BO3)(SiO4)(OH)13O5
Colour:
Colourless to light pink
Lustre:
Vitreous
Specific Gravity:
5.973 (Calculated)
Crystal System:
Triclinic
Name:
Named for dr Roy McG. Miller for his contributions to the knowledge of the Namibia's geology
Chemically quite similar to britvinite; structurally related to britvinite and molybdophyllite. The combination of anion types in roymillerite is unique.
Crystal structure details:
- pyrophyllite-type TOT-modules of the Mg9(OH)8[(Si,Al)10O28] composition
- I-blocks of the Pb24(OH)6O4(CO3)10(BO3,SiO4) composition
Crystal structure details:
- pyrophyllite-type TOT-modules of the Mg9(OH)8[(Si,Al)10O28] composition
- I-blocks of the Pb24(OH)6O4(CO3)10(BO3,SiO4) composition
Unique Identifiers
Mindat ID:
50357
Long-form identifier:
mindat:1:1:50357:6
IMA Classification of Roymillerite
Approved
IMA Formula:
Pb2+24Mg9(Si10O28)(CO3)10(BO3)(SiO4)(OH)13O5
Approval year:
2016
First published:
2017
Type description reference:
Chukanov, Nikita V., Jonsson, Erik, Aksenov, Sergey M., Britvin, Sergey N., Rastsvetaeva, Ramiza K., Belakovskiy, Dmitriy I., Van, Konstantin V. (2017) Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry. Physics and Chemistry of Minerals, 44 (10) 685-699 doi:10.1007/s00269-017-0893-2
Classification of Roymillerite
9.EG.70
9 : SILICATES (Germanates)
E : Phyllosilicates
G : Double nets with 6-membered and larger rings
9 : SILICATES (Germanates)
E : Phyllosilicates
G : Double nets with 6-membered and larger rings
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 |
|---|---|---|
| Roy | 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 Roymillerite
Vitreous
Transparency:
Transparent
Comment:
strong
Colour:
Colourless to light pink
Cleavage:
Perfect
on (001)
on (001)
Density:
5.973 g/cm3 (Calculated)
Optical Data of Roymillerite
Type:
Biaxial (-)
RI values:
nα = 1.86(1) nβ = 1.94(1) nγ = 1.94(1)
2V:
Measured: 5° (5)
Max. Birefringence:
δ = 0.080
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:
Very High (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.
Chemistry of Roymillerite
Mindat Formula:
Pb24Mg9(Si10O28)(CO3)10(BO3)(SiO4)(OH)13O5
Element Weights:
Crystallography of Roymillerite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 9.316(1) Å, b = 9.316(1) Å, c = 26.463(4) Å
α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°
α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°
Ratio:
a:b:c = 1 : 1 : 2.841
Unit Cell V:
1971.2 ų
Z:
1
Morphology:
Platy single-crystal grains
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 25.9 Å | (100) |
| 13.1 Å | (11) |
| 3.480 Å | (12) |
| 3.378 Å | (14) |
| 3.282 Å | (16) |
| 3.185 Å | (12) |
| 2.684 Å | (16) |
| 2.382 Å | (11) |
Reference:
Chukanov, Nikita V., Jonsson, Erik, Aksenov, Sergey M., Britvin, Sergey N., Rastsvetaeva, Ramiza K., Belakovskiy, Dmitriy I., Van, Konstantin V. (2017) Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry. Physics and Chemistry of Minerals, 44 (10) 685-699 doi:10.1007/s00269-017-0893-2
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Type Occurrence of Roymillerite
General Appearance of Type Material:
Platy single-crystal grains, up to 1.5 x 0.3 mm in size
Place of Conservation of Type Material:
Cotype: mineralogical collections of the Swedish Museum of Natural History, Stockholm, Sweden (catalogue # 20080176)
Empirical Formula of Type Material:
Pb24.12Mg8.74Mn1.25Fe0.94B1.03Al1.04C9.46Si9.39H14.27O83
Chemical Analysis of Type Material:
| MgO | 4.93 % |
|---|---|
| MnO | 1.24 % |
| FeO | 0.95 % |
| PbO | 75.38 % |
| B2O3 | 0.50 % |
| Al2O3 | 0.74 % |
| CO2 | 5.83 % |
| SiO2 | 7.90 % |
| H2O | 1.8 % |
| Total: | 99.27 % |
Associated Minerals at Type Locality:
Reference:
Chukanov, Nikita V., Jonsson, Erik, Aksenov, Sergey M., Britvin, Sergey N., Rastsvetaeva, Ramiza K., Belakovskiy, Dmitriy I., Van, Konstantin V. (2017) Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry. Physics and Chemistry of Minerals, 44 (10) 685-699 doi:10.1007/s00269-017-0893-2
Synonyms of Roymillerite
Other Language Names for Roymillerite
Dutch:Roymilleriet
German:Roymillerit
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.EG.05 | Cymrite | BaAl2Si2(O,OH)8 · H2O |
| 9.EG.10 | Naujakasite | (Na,K)6(Fe2+,Mn2+,Ca)(Al,Fe)4Si8O26 |
| 9.EG.10 | Manganonaujakasite | Na6(Mn2+,Fe2+)Al4Si8O26 |
| 9.EG.15 | Dmisteinbergite | Ca(Al2Si2O8) |
| 9.EG.20 | Kampfite | Ba12(Si11Al5)O31(CO3)8Cl5 |
| 9.EG.25 | Vertumnite | Ca4Al4Si4O6(OH)24 · 3H2O |
| 9.EG.30 | Eggletonite | (Na,K,Ca)xMn6(Si,Al)10O24(OH)4 · nH2O (x = 1-2; n = 7-11) |
| 9.EG.30 | Ganophyllite | (K,Na)xMn2+6(Si,Al)10O24(OH)4 · nH2O (x = 1-2; n = 7-11) |
| 9.EG.30 | Tamaite | (Ca,K,Na)xMn6(Si,Al)10O24(OH)4 · nH2O (x = 1-2; n = 7-11) |
| 9.EG.35 | Zussmanite | K(Fe,Mg,Mn)13(Si,Al)18O42(OH)14 |
| 9.EG.35 | Coombsite | KMn2+13(Si,Al)18O42(OH)14 |
| 9.EG.40 | 'Chalcodite' | K(Fe3+,Mg,Fe2+)8(Si,Al)12(O,OH)27 |
| 9.EG.40 | Parsettensite | (K,Na,Ca)7.5(Mn,Mg)49Si72O168(OH)50 · nH2O |
| 9.EG.40 | Lennilenapeite | K4Mn2+48[Si64Al8]O164(OH)52 · nH2O |
| 9.EG.40 | Stilpnomelane | K4Fe2+48[Si64Al8]O164(OH)52 · nH2O |
| 9.EG.45 | Latiumite | (Ca,K)4(Si,Al)5O11(SO4,CO3) |
| 9.EG.45 | Levantite | KCa3Al2(SiO4)(Si2O7)(PO4) |
| 9.EG.45 | Tuscanite | KCa6(Si,Al)10O22(SO4,CO3)2(OH) · H2O |
| 9.EG.50 | Jagoite | Pb18Fe3+4[Si4(Si,Fe3+)6][Pb4Si16(Si,Fe)4]O82Cl6 |
| 9.EG.50 | Friisite | Pb8Al3Si8O27Cl3 |
| 9.EG.55 | Wickenburgite | CaPb3Al2Si10O24(OH)6 |
| 9.EG.60 | Hyttsjöite | Pb18Ba2Ca5Mn2+2Fe3+2Si30O90Cl · 6H2O |
| 9.EG.65 | Armbrusterite | K5Na7Mn15[(Si9O22)4](OH)10 · 4H2O |
| 9.EG.70 | Britvinite | [Pb7(OH)3F(BO3)2(CO3)][Mg4.5(OH)3(Si5O14)] |
| 9.EG.75 | Kayupovaite | Na2Mn10[(Si14Al2)O38(OH)8] · 7H2O |
| 9.EG.75 | 'UM1989-30-SiO:AlBaCaFeHKMgMn' | (Ba,Ca)(Mn,Fe,Mg)22(Si,Al)32O76(OH)16 · 12H2O |
| 9.EG.75 | Bannisterite | CaMn2+10(Si14Al2)O38(OH)8 · nH2O |
Other Information
IR Spectrum:
Confirms the presence of the britvinite-type tetrahedral sheets, and the complex anions given in the formula
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 Roymillerite
mindat.org URL:
https://www.mindat.org/min-50357.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Roymillerite
Reference List:
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2016) New minerals and nomenclature modifications approved in 2016, CNMNC Newsletter No. 33. Mineralogical Magazine, 80 (6) 1135-1144 doi:10.1180/minmag.2016.080.085
Chukanov, Nikita V., Jonsson, Erik, Aksenov, Sergey M., Britvin, Sergey N., Rastsvetaeva, Ramiza K., Belakovskiy, Dmitriy I., Van, Konstantin V. (2017) Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry. Physics and Chemistry of Minerals, 44 (10) 685-699 doi:10.1007/s00269-017-0893-2
Localities for Roymillerite
Showing 1 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.
Namibia (TL) | |
| Hålenius et al. (2016) +2 other references |
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Kombat Mine, Kombat, Otavi Constituency, Otjozondjupa Region, Namibia