Macfallite Mineral Data

General Macfallite Information

Chemical Formula:

Ca2(Mn+++,Al)3(SiO4)(Si2O7)(OH)3

Composition:

Molecular Weight = 544.17 gm

Sodium 0.04 % Na 0.06 % Na₂O

Calcium 14.95 % Ca 20.92 % CaO

Magnesium 0.40 % Mg 0.67 % MgO

Manganese 25.34 % Mn 36.41 % Mn₂O₃

Aluminum 1.34 % Al 2.53 % Al₂O₃

Vanadium 0.09 % V 0.14 % V₂O₃

Copper 0.35 % Cu 0.44 % CuO

Silicon 15.74 % Si 33.68 % SiO₂

Hydrogen 0.58 % H 5.16 % H₂O

Oxygen 41.16 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca_2.03Na_0.01Mn³⁺_2.51Al_0.27Mg_0.09Cu_0.03V³⁺_0.01Si_3.05O_10.88(OH)_3.12

Environment:

Associated with other Mn-silicates.

IMA Status:

Approved IMA 1979

Locality:

Manganese Lake, Copper Harbor, Keweenaw County, Michigan, USA. Link to MinDat.org Location Data.

Name Origin:

Named for Russell P. MacFall, a dedicated amateur mineralogist.

Name Pronunciation:

Macfallite + Pronunciation

Synonym:

ICSD 1612

PDF 42-601

Macfallite Image

Images:

Macfallite Johnsenite-(Ce) Braunite-I

Comments: Tiny - less than 1mm - maroon crystals of mcfallite suspended as inclusions in massive quartz along with larger spots of brown johnsenite-(Ce) and braunite.
Location: Artur mine, Jaguaracu, Minas Gerais, Brazil. Scale: Overall 3 x 2.5 slab.
© Tom Loomis / Dakota Matrix

Macfallite Crystallography

Axial Ratios:

a:b:c =1.4754:1:1.6828

Cell Dimensions:

a = 8.959, b = 6.072, c = 10.218, Z = 2; beta = 110.75° V = 519.79 Den(Calc)= 3.48

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/m

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

By Intensity(I/I_o): 3.399(1), 3.892(0.7), 2.962(0.5),

Physical Properties of Macfallite

Cleavage:

{001} Perfect

Color:

Brown, Maroon, Reddish brown, Pink.

Density:

3.43

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

5-5.5 - Apatite-Knife Blade

Luster:

Vitreous - Silky

Streak:

brown

Optical Properties of Macfallite

Gladstone-Dale:

CI meas= 0.07 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= 0.084 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2281,KPDmeas= 0.2314,KC= 0.2489
Ncalc = 1.85 - 1.87

Optical Data:

Biaxial (-), a=1.773-1.775, b=1.795, g=1.81-1.815, bire=0.0370-0.0400, 2V(Calc)=78-88, 2V(Meas)=86.

Pleochroism (x):

colorless or yellow.

Pleochroism (y):

light brown or light brown.

Pleochroism (z):

brownish red or dark brown.

Calculated Properties of Macfallite

Electron Density:

Bulk Density (Electron Density)=3.37 gm/cc
note: Specific Gravity of Macfallite =3.43 gm/cc.

Fermion Index:

Fermion Index = 0.0081559315
Boson Index = 0.9918440685

Photoelectric:

PE_Macfallite= 9.10 barns/electron
U=PE_Macfallite x rElectron Density= 30.63 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Macfallite is Not Radioactive

Macfallite Classification

Dana Class:

58.02.03.02 (58)Sorosilicate Insular, Mixed, Single, and Larger Tetrahedral Groups

(58.02)with cations in [6] and higher coordination; single and double groups (n=1,2)

(58.02.03)Sursassite and related species

58.02.03.01 Sursassite Mn2Al3(SiO4)(Si2O7)(OH)3 P 2₁/m 2/m

58.02.03.02 Macfallite Ca2(Mn,Al)3(SiO4)(Si2O7)(OH)3 P 2₁/m 2/m

Strunz Class:

09.BG.15 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BG -Sorosilicates with mixed SiO4 and Si2O7 groups;

09.BG.15 Macfallite Ca2(Mn,Al)3(SiO4)(Si2O7)(OH)3 P 2₁/m 2/m

09.BG.15 Sursassite Mn2Al3(SiO4)(Si2O7)(OH)3 P 2₁/m 2/m

Other Macfallite Information

References:

NAME( Dana8) PHYS. PROP.(Dana8, AmMin v93:1851) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Macfallite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Print or Cut-and-Paste your Macfallite Specimen Label here :

Macfallite

Ca2(Mn+++,Al)3(SiO4)(Si2O7)(OH)3
Dana No: 58.02.03.02 Strunz No: 09.BG.15
Locality:

Notes:

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