Mcgillite
A valid IMA mineral species
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About Mcgillite
Formula:
(Mn,Fe)8Si6O15(OH)8Cl2
Hardness:
5
Crystal System:
Monoclinic
Member of:
Name:
Named by Gabrielle Donnay, M. Bétournay, and G. Hamil in recognition of McGill University, Montreal, Quebec, Canada and its contributions to mineralogy.
Isostructural with:
May be regarded as an ordered equivalent of friedelite (Ozawa et al., 1983).
Chemically very similar to pyrosmalite-(Mn).
Chemically very similar to pyrosmalite-(Mn).
Unique Identifiers
Mindat ID:
2613
Long-form identifier:
mindat:1:1:2613:6
GUID
(UUID V4):
(UUID V4):
b026c162-b7f9-49d8-9dd7-b9a372a025fc
IMA Classification of Mcgillite
Classification of Mcgillite
9.EE.10
9 : SILICATES (Germanates)
E : Phyllosilicates
E : Single tetrahedral nets of 6-membered rings connected by octahedral nets or octahedral bands
9 : SILICATES (Germanates)
E : Phyllosilicates
E : Single tetrahedral nets of 6-membered rings connected by octahedral nets or octahedral bands
72.4.1b.2
72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
4 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with 4-, 6-, and 12-membered rings
72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
4 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with 4-, 6-, and 12-membered rings
17.3.16
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.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Symbol | Source | Reference |
---|---|---|
Mcg | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Mcg | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of Mcgillite
Hardness:
5 on Mohs scale
Optical Data of Mcgillite
Type:
Biaxial (-)
RI values:
nω = 1.669 n = 1.6415
Birefringence:
0.027
Max Birefringence:
δ = 1.669
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:
Moderate
Dispersion:
relatively weak
Pleochroism:
Non-pleochroic
Chemistry of Mcgillite
Mindat Formula:
(Mn,Fe)8Si6O15(OH)8Cl2
Common Impurities:
As,Zn,Mg,Ca,H2O
Crystallography of Mcgillite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C1 2/m 1
Cell Parameters:
a = 23.31 Å, b = 13.45 Å, c = 7.42 Å
β = 105.17°
β = 105.17°
Ratio:
a:b:c = 1.733 : 1 : 0.552
Unit Cell V:
2,245.25 ų (Calculated from Unit Cell)
Twinning:
Universal, repeated about monoclinic [110] and [1-10], composition plane {001}, giving pseudorhombohedral symmetry.
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
11.67 Å | (20) |
7.16 Å | (70) |
6.75 Å | (10) |
6.50 Å | (10) |
5.44 Å | (10) |
3.570 Å | (40) |
2.888 Å | (60) |
2.560 Å | (100) |
2.409 Å | (20) |
2.112 Å | (40) |
1.971 Å | (20) |
1.727 Å | (20) |
1.683 Å | (40) |
1.638 Å | (20) |
1.619 Å | (20) |
1.524 Å | (10) |
1.454 Å | (10) |
1.420 Å | (20) |
1.356 Å | (20) |
1.317 Å | (10) |
1.292 Å | (10) |
1.205 Å | (10) |
1.167 Å | (10) |
1.100 Å | (10) |
1.0897 Å | (10) |
1.0795 Å | (20) |
Comments:
Nearly identical to that of friedelite. Data from: Donnay, G., M. Bétournay, and G. Hamill (1980): McGillite, a new manganous hydroxychlorosilicate. Canadian Mineralogist 18, 31-36. [Abstract: American Mineralogist (1981): 66: 1276.]
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
High-𝑇 alteration and/or metamorphism | |
32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Mcgillite
Synonyms of Mcgillite
Other Language Names for Mcgillite
Relationship of Mcgillite to other Species
Member of:
Other Members of this group:
Friedelite | Mn2+8Si6O15(OH,Cl)10 | Mon. 2/m : B2/m |
Nelenite | (Mn,Fe)16(Si12O30)(OH)14[As3+3O6(OH)3] | Trig. 3m (3 2/m) : R3m |
Pyrosmalite-(Fe) | Fe2+8Si6O15(OH,Cl)10 | Trig. 3m (3 2/m) : P3m1 |
Pyrosmalite-(Mn) | Mn2+8Si6O15(OH,Cl)10 | Trig. 3m (3 2/m) : P3m1 |
Schallerite | Mn2+16As3Si12O36(OH)17 | Trig. 3m : P3m1 |
Common Associates
Associated Minerals Based on Photo Data:
5 photos of Mcgillite associated with Sphalerite | ZnS |
3 photos of Mcgillite associated with Boulangerite | Pb5Sb4S11 |
3 photos of Mcgillite associated with Calcite | CaCO3 |
3 photos of Mcgillite associated with Pyrite | FeS2 |
3 photos of Mcgillite associated with Quartz | SiO2 |
Related Minerals - Strunz-mindat Grouping
9.EE. | Cairncrossite | Sr2Ca7-xNa2x(Si4O10)4(OH)2(H2O)15-x |
9.EE.05 | Bementite | Mn7Si6O15(OH)8 |
9.EE.07 | Innsbruckite | Mn33(Si2O5)14(OH)38 |
9.EE.10 | Brokenhillite | Mn8Si6O15(OH)10 |
9.EE.10 | Pyrosmalite-(Fe) | Fe2+8Si6O15(OH,Cl)10 |
9.EE.10 | Friedelite | Mn2+8Si6O15(OH,Cl)10 |
9.EE.10 | Pyrosmalite-(Mn) | Mn2+8Si6O15(OH,Cl)10 |
9.EE.15 | Nelenite | (Mn,Fe)16(Si12O30)(OH)14[As3+3O6(OH)3] |
9.EE.15 | Schallerite | Mn2+16As3Si12O36(OH)17 |
9.EE.20 | Palygorskite | ◻Al2Mg2◻2Si8O20(OH)2(H2O)4 · 4H2O |
9.EE.20 | Tuperssuatsiaite | Fe3+Fe3+2(Na◻)◻2Si8O20(OH)2(H2O)4 · 2H2O |
9.EE.20 | Yofortierite | Mn2+Mn2+2Mn2+2◻2Si8O20(OH)2(H2O)4 · 4H2O |
9.EE.20 | Windhoekite | Fe3+(Fe3+1.67◻0.33)Ca2◻2Si8O20(OH)2(H2O)4(OH)2 · 6H2O |
9.EE.20 | Unnamed (Na-Ca-Fe-Silicate-Hydrate) | NaCa(Fe2+,Al,Mn)5[Si8O19(OH)](OH)7 · 5H2O |
9.EE.20 | Windmountainite | ◻Fe3+2Mg2◻2Si8O20(OH)2(H2O)4 · 4H2O |
9.EE.25 | Falcondoite | (Ni,Mg)4Si6O15(OH)2 · 6H2O |
9.EE.25 | Loughlinite | Na2Mg3Si6O16 · 8H2O |
9.EE.25 | Sepiolite | Mg4(Si6O15)(OH)2 · 6H2O |
9.EE.25 | Kalifersite | (K,Na)5Fe3+7Si20O50(OH)6 · 12H2O |
9.EE.30 | Gyrolite | NaCa16Si23AlO60(OH)8 · 14H2O |
9.EE.30 | Orlymanite | Ca4Mn3Si8O20(OH)6 · 2H2O |
9.EE.30 | Tungusite | Ca4Fe2Si6O15(OH)6 |
9.EE.35 | Reyerite | (Na,K)2Ca14(Si,Al)24O58(OH)8 · 6H2O |
9.EE.35 | Truscottite | (Ca,Mn)14Si24O58(OH)8 · 2H2O |
9.EE.35 | Kodamaite | Na3(Ca5Na)Si16O36(OH)4F2 · (14-x)H2O |
9.EE.40 | Natrosilite | Na2Si2O5 |
9.EE.45 | Makatite | Na2Si4O8(OH)2 · 4H2O |
9.EE.50 | Varennesite | Na8Mn2Si10O25(OH,Cl)2 · 12H2O |
9.EE.55 | Raite | Mn2+Mn2+2Na2(◻1.75Ti0.25)Si8O20(OH)2(H2O)4 · Na(H2O)6 |
9.EE.60 | Intersilite | Na6Mn2+Ti[Si10O24(OH)](OH)3 · 4H2O |
9.EE.65 | Shafranovskite | Na3K2(Mn,Fe,Na)4[Si9(O,OH)27](OH)2 · nH2O |
9.EE.65 | Zakharovite | Na4Mn5Si10O24(OH)6 · 6H2O |
9.EE.70 | Zeophyllite | Ca13Si10O28(OH)2F8 · 6H2O |
9.EE.75 | Minehillite | (K,Na)2-3Ca28Zn4Al4Si40O112(OH)16 |
9.EE.80 | Fedorite | (Na,K)2-3(Ca4Na3)Si16O38(OH,F)2 · 3.5H2O |
9.EE.80 | Martinite | (Na,◻,Ca)12Ca4(Si,S,B)14B2O38(OH,Cl)2F2 · 4H2O |
9.EE.80 | Ellingsenite | Na5Ca6Si18O38(OH)13 · 6H2O |
9.EE.85 | Lalondeite | (Na,Ca)6(Ca,Na)3Si16O38(F,OH)2 · 3H2O |
Fluorescence of Mcgillite
Not fluorescent in UV
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 Mcgillite
mindat.org URL:
https://www.mindat.org/min-2613.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Mcgillite
Reference List:
Localities for Mcgillite
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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Canada (TL) | |
| DONNAY et al. (1980) +2 other references |
Japan | |
| DONNAY et al. (1980) |
Romania | |
Hirtopanu (2006) | |
| minerals-of-the-carpathians.eu (2008) |
Slovakia | |
| Martin Števko & Pavol Myšľan |
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Sullivan Mine, Kimberley, Fort Steele Mining Division, British Columbia, Canada