Muirite
A valid IMA mineral species
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About Muirite
John Muir
Formula:
Ba10(Ca2Mn2+Ti)[Si8O24]O2Cl10
The IMA formula for muirite with 10 Si differs from related species ferrimuirite (8 Si), and may be inconsistent with the 8-Si ring structure of the muirite group. The mindat formula for muirite is modeled after the formula for ferrimuirite.
Colour:
Orange
Lustre:
Sub-Vitreous
Hardness:
2½
Specific Gravity:
3.86
Crystal System:
Tetragonal
Name:
Named by J.T. Alfors, M.C. Stinson, R.A. Matthews, and A. Pabst in 1965 in honor of John Muir (21 April 1838, Dunbar, Scotland - 24 December 1914, Los Angeles, California, US), also known as "John of the Mountains". Muir was a geologist and explorer, naturalist, author, environmental philosopher, and glaciologist. He was an early advocate for the preservation of wilderness in the United States and founded the Sierra Club.
This page provides mineralogical data about Muirite.
Unique Identifiers
Mindat ID:
2804
Long-form identifier:
mindat:1:1:2804:8
Similar Names
| Marrite | A valid IMA mineral species - grandfathered | AgPbAsS3 |
| Meierite | A valid IMA mineral species | Ba44Si66Al30O192Cl25(OH)33 |
| Mohrite | A valid IMA mineral species | (NH4)2Fe(SO4)2 · 6H2O |
| Moiraite | A valid IMA mineral species - pending publication | Pb12Sb8As8S36 |
| Mooreite | A valid IMA mineral species - grandfathered | Mg9◻2Mn2Zn4(SO4)2(OH)26 · 8H2O |
| Mourite | A valid IMA mineral species | UMo5O12(OH)10 |
| Munirite | A valid IMA mineral species | NaVO3 · 1.9H2O |
IMA Classification of Muirite
Approved
IMA Formula:
Ba10Ca2Mn2+Ti4+Si10O30(OH,Cl,F)10
Approval year:
1964
First published:
1965
Classification of Muirite
9.CN.05
9 : SILICATES (Germanates)
C : Cyclosilicates
N : [Si8O24]16- 8-membered rings
9 : SILICATES (Germanates)
C : Cyclosilicates
N : [Si8O24]16- 8-membered rings
62.1.1.1
62 : CYCLOSILICATES Eight-Membered Rings
1 : Eight-Membered Rings with 8-membered and larger rings
62 : CYCLOSILICATES Eight-Membered Rings
1 : Eight-Membered Rings with 8-membered and larger rings
17.3.18
17 : Silicates Containing other Anions
3 : Silicates with chloride (including aluminosilicates)
17 : Silicates Containing other Anions
3 : Silicates with chloride (including aluminosilicates)
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 |
|---|---|---|
| Mui | 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 Muirite
Sub-Vitreous
Transparency:
Transparent, Translucent
Colour:
Orange
Streak:
Pale orange
Hardness:
2½ on Mohs scale
Cleavage:
Poor/Indistinct
Indistinct on {001} and {100}
Indistinct on {001} and {100}
Density:
3.86(2) g/cm3 (Measured) 3.88 g/cm3 (Calculated)
Optical Data of Muirite
Type:
Uniaxial (+)
RI values:
nω = 1.697 nε = 1.704
Max. Birefringence:
δ = 0.007
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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Visible
Comments:
O = orange
E = colorless
E = colorless
Chemistry of Muirite
Mindat Formula:
Ba10(Ca2Mn2+Ti)[Si8O24]O2Cl10
The IMA formula for muirite with 10 Si differs from related species ferrimuirite (8 Si), and may be inconsistent with the 8-Si ring structure of the muirite group. The mindat formula for muirite is modeled after the formula for ferrimuirite.
The IMA formula for muirite with 10 Si differs from related species ferrimuirite (8 Si), and may be inconsistent with the 8-Si ring structure of the muirite group. The mindat formula for muirite is modeled after the formula for ferrimuirite.
Element Weights:
Common Impurities:
Al,Fe,Mg,Sr,K,H2O
Crystallography of Muirite
Crystal System:
Tetragonal
Class (H-M):
4/mmm(4/m2/m2/m) - Ditetragonal Dipyramidal
Space Group:
P4/mmm
Cell Parameters:
a = 14.000(3) Å, c = 5.625(2) Å
Ratio:
a:c = 1 : 0.402
Unit Cell V:
1,102.50 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Subhedral to euhedral crystals not uncommon.
The common forms are {001} and {100}; other forms include {110} and a few (h01) faces.
The common forms are {001} and {100}; other forms include {110} and a few (h01) faces.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
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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) |
|---|---|---|---|---|---|---|---|
| 0018352 | Muirite | Malinovskii Y A, Pobedimskaya E A, Belov N V (1975) Crystal structure of muirite Ba9(Ca,Ba)(Ca,Ti)4(OH)8[Si8O24](Cl,OH)8 Soviet Physics Doklady 20 163-164 | 1975 | Big Creek, Fresno County, California, USA | 0 | 293 | |
| 0020849 | Muirite | Khan A A, Baur W H (1971) Eight-membered cyclosilicate rings in muirite Science 173 916-918 | 1971 | Esquire No. 7 mine, Big Creek, Fresno County, California | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.91 Å | (100) |
| 4.42 Å | (75) |
| 3.73 Å | (60) |
| 3.51 Å | (60) |
| 3.31 Å | (60) |
| 3.60 Å | (50) |
| 2.814 Å | (40) |
| 2.743 Å | (40) |
| 2.154 Å | (40) |
| 2.094 Å | (40) |
| 10.0 Å | (25) |
| 2.607 Å | (25) |
| 2.214 Å | (25) |
| 2.042 Å | (25) |
Comments:
Esquire No. 7 claim, California, USA.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Muirite
General Appearance of Type Material:
Anhedral grains. Also subhedral to euhedral tetragonal crystals averaging 0.5 mm and up to 3 mm in size.
Place of Conservation of Type Material:
California Divisions of Mines & Geology, USA.
Geological Setting of Type Material:
Sanbornite-quartz-bearing metamorphic rock.
Synonyms of Muirite
Other Language Names for Muirite
Common Associates
Associations Based on Photo Data:
| 12 photos of Muirite associated with Sanbornite | BaSi2O5 |
| 7 photos of Muirite associated with Quartz | SiO2 |
| 4 photos of Muirite associated with Pyrrhotite | Fe1-xS |
| 4 photos of Muirite associated with Cerchiaraite-(Fe) | Ba4Fe3+4O3(OH)3(Si4O12)[Si2O3(OH)4]Cl |
| 4 photos of Muirite associated with Ferrimuirite | Ba10(Ca2Fe3+2)[Si8O24]O2Cl10 |
| 4 photos of Muirite associated with Pellyite | Ba2CaFe2+2Si6O17 |
| 4 photos of Muirite associated with Witherite | BaCO3 |
| 2 photos of Muirite associated with Titantaramellite | Ba4(Ti,Fe3+,Fe2+,Mg)4(B2Si8O27)O2Clx |
| 1 photo of Muirite associated with Fresnoite | Ba2Ti(Si2O7)O |
| 1 photo of Muirite associated with Uvarovite | Ca3Cr3+2(SiO4)3 |
Related Minerals - Strunz-mindat Grouping
| 9.CN.05 | Ferrimuirite | Ba10(Ca2Fe3+2)[Si8O24]O2Cl10 |
Fluorescence of Muirite
None.
Other Information
Thermal Behaviour:
Gives off water in a closed test tube and fuses at about 3.
Heated rapidly to 900 °C in an electric furnace, it turns brown. Further heating turns it pinkish and it partially melts at 1100 °C. At 1200 °C it completely melts to a pale lavender glass.
Heated rapidly to 900 °C in an electric furnace, it turns brown. Further heating turns it pinkish and it partially melts at 1100 °C. At 1200 °C it completely melts to a pale lavender glass.
Notes:
Decomposed by dilute hydrochloric and nitric acids. Loses its color and disintegrates to a white or colorless residue. Not affected by sulfuric acid, acetic acid, or concentrated sodium hydroxide.
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 Muirite
mindat.org URL:
https://www.mindat.org/min-2804.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Muirite
Reference List:
Alfors, John T., Stinson, Melvin C., Matthews, Robert A., Pabst, Adolf (1965) Seven new barium minerals from eastern Fresno County, California. American Mineralogist, 50 (3-4) 314-340
Alfors, John T., Putman, George W. (1965) Revised chemical analyses of traskite, verplanckite, and muirite from Fresno County, California. American Mineralogist, 50 (9) 1500-1503
Localities for Muirite
Showing 3 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.
Canada | |
| Alfors et al. (1984) +3 other references |
USA (TL) | |
| Walstrom (n.d.) +5 other references |
| Pabst et al. (1984) |
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Gun claim, Wilson Lake, Itsi Mountain, Watson Lake mining district, Yukon, Canada