Mcgillite Mineral Data

Mcgillite Mineral Data +

General Mcgillite Information

Chemical Formula:

(Mn,Fe++)8Si6O15(OH)8Cl2

Composition:

Molecular Weight = 1,038.40 gm

Magnesium 0.47 % Mg 0.78 % MgO

Manganese 37.03 % Mn 47.82 % MnO

Iron 3.23 % Fe 4.15 % FeO

Silicon 16.23 % Si 34.72 % SiO₂

Hydrogen 0.78 % H 6.94 % H₂O

Chlorine 6.83 % Cl 6.83 % Cl

- % Cl -1.54 % -O=Cl₂

Oxygen 35.44 % O

______ ______

100.00 % 99.69 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₇Fe²⁺_0.6Mg_0.2Si₆O₁₅(OH)₈Cl₂

Environment:

Open space fracture fillings in a manganese-rich section of quartzite and argillite in a metamorphosed Pb-Zn orebody.

IMA Status:

Approved IMA 1980

Locality:

In the Sullivan mine, Kimberley, Kootenay district, British Columbia, Canada. Link to MinDat.org Location Data.

Name Origin:

Named for McGill University, Montreal, Quebec, Canada.

Synonym:

IMA1979-024

Mcgillite Image

Images:

Mcgillite

Comments: Pink crystalline mcgillite with galena.
Location: Near Kimberley, Kootenay District, British Columbia, Canada. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Mcgillite Crystallography

Axial Ratios:

a:b:c =1.732:1:0.5515

Cell Dimensions:

a = 23.312, b = 13.459, c = 7.423, Z = 4; beta = 105.17° V = 2,247.85 Den(Calc)= 3.07

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.56(1), 7.16(0.7), 2.888(0.6),

Physical Properties of Mcgillite

Cleavage:

[0001] Good

Color:

Light pink, Dark pink.

Density:

2.98

Diaphaniety:

Transparent

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Pseudo Hexagonal - Crystals show a hexagonal outline.

Hardness:

5 - Apatite

Luster:

Pearly

Streak:

reddish white

Optical Properties of Mcgillite

Gladstone-Dale:

CI meas= -0.002 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.028 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2148,KPDmeas= 0.2213,KC= 0.2209

Optical Data:

Biaxial (-), a=1.64-1.643, b=1.667-1.67, g=1.667-1.67, bire=0.0270

Calculated Properties of Mcgillite

Electron Density:

r_electron=2.89 gm/cc
note: r_Mcgillite=2.98 gm/cc.

Fermion Index

Fermion Index = 0.0089
Boson Index = 0.9911

Photoelectric:

PE_Mcgillite= 11.52 barns/electron
U=PE_Mcgillite x r_electron= 33.27 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Mcgillite is Not Radioactive

Mcgillite Classification

Dana Class:

72.4.1b.2 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.4)with 4-, 6-, and 12-membered rings

(72.4.1b)Pyrosmalite group (Friedelite subgroup)

72.4.1b.1 Friedelite Mn8Si6O15(OH,Cl)10 C 2/m 2/m

72.4.1b.2 Mcgillite (Mn,Fe)8Si6O15(OH)8Cl2 C 2/m 2/m

72.4.1b.3 Nelenite (Mn,Fe)16Si12As3O36(OH)17 R 3m 3 2/m

Strunz Class:

VIII/H.28-80 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with other simple layers, [Si6O15]6- and others

VIII/H.28 - Pyrosmalite series

VIII/H.28-10 Ferropyrosmalite (Fe,Mn)8Si6O15(OH,Cl)10 P 3m1 3 2/m

VIII/H.28-20 Manganpyrosmalite (Mn,Fe)8Si6O15(OH,Cl)10 P 3m1 3 2/m

VIII/H.28-30 Brokenhillite* (Mn,Fe)32[Si24O60]OH29Cl11 P 6₃mc 6mm

VIII/H.28-40 Nelenite (Mn,Fe)16Si12As3O36(OH)17 R 3m 3 2/m

VIII/H.28-50 Schallerite Mn16[AsO2OH][Si12O30](OH)14 P 3m1 ? 3m

VIII/H.28-70 Friedelite Mn8Si6O15(OH,Cl)10 C 2/m 2/m

VIII/H.28-80 Mcgillite (Mn,Fe)8Si6O15(OH)8Cl2 C 2/m 2/m

VIII/H.28-90 Bementite Mn8Si6O15(OH)10 P 2₁/c 2/m

VIII/H.28-100 Varennesite Na8Mn2Si10O25(OH,Cl)2·12(H2O) C mcm 2/m 2/m 2/m

Other Mcgillite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

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Mcgillite

(Mn,Fe++)8Si6O15(OH)8Cl2
Dana No: 72.4.1b.2 Strunz No: VIII/H.28-80
Locality:

Notes: