Mineralogy Database

Macfallite Mineral Data

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General Macfallite Information

Help on Chemical  Formula: Chemical Formula: Ca2(Mn+++,Al)3(SiO4)(Si2O7)(OH)3
Help on Composition: 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
Help on Empirical Formula: Empirical Formula: Ca2.03Na0.01Mn3+2.51Al0.27Mg0.09Cu0.03V3+0.01Si3.05O10.88(OH)3.12
Help on Environment: Environment: Associated with other Mn-silicates.
Help on IMA Status: IMA Status: Approved IMA 1979
Help on Locality: Locality: Manganese Lake, Copper Harbor, Keweenaw County, Michigan, USA. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Russell P. MacFall, a dedicated amateur mineralogist.
Help on Name Pronunciation: Name Pronunciation: Macfallite + Pronunciation Say MACFALLITE
Help on Synonym: Synonym: ICSD 1612
  PDF 42-601

Macfallite Image

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  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

Help on Axial Ratios: Axial Ratios: a:b:c =1.4754:1:1.6828
Help on Cell Dimensions: Cell Dimensions: a = 8.959, b = 6.072, c = 10.218, Z = 2; beta = 110.75° V = 519.79 Den(Calc)= 3.48
Help on Crystal System: 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/Io): 3.399(1), 3.892(0.7), 2.962(0.5),

Physical Properties of Macfallite

Help on Cleavage: Cleavage: {001} Perfect
Help on Color: Color: Brown, Maroon, Reddish brown, Pink.
Help on Density: Density: 3.43
Help on Habit: Habit: Acicular - Occurs as needle-like crystals.
Help on Habit: Habit: Aggregates - Made of numerous individual crystals or clusters.
Help on Habit: Habit: Twinning Common - Crystals are usually twinned.
Help on Hardness: Hardness: 5-5.5 - Apatite-Knife Blade
Help on Luster: Luster: Vitreous - Silky
Help on Streak: Streak: brown

Optical Properties of Macfallite

Help on Gladstone-Dale: 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
Help on Optical Data: 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.
Help on Pleochroism (x): Pleochroism (x): colorless or yellow.
Help on Pleochroism (y): Pleochroism (y): light brown or light brown.
Help on Pleochroism (z): Pleochroism (z): brownish red or dark brown.

Calculated Properties of Macfallite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.37 gm/cc
note: Specific Gravity of Macfallite =3.43 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0081559315
Boson Index = 0.9918440685
Help on Photoelectric: Photoelectric: PEMacfallite = 9.10 barns/electron
U=PEMacfallite x rElectron Density= 30.63 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Macfallite is Not Radioactive

Macfallite Classification

Help on  Dana Class: Dana Class: (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 Sursassite Mn2Al3(SiO4)(Si2O7)(OH)3 P 21/m 2/m Macfallite Ca2(Mn,Al)3(SiO4)(Si2O7)(OH)3 P 21/m 2/m
Help on  Strunz Class: 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

Help on References: References: NAME( Dana8) PHYS. PROP.(Dana8, AmMin v93:1851) OPTIC PROP.(Dana8)
Help on See Also: 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

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Dana No: Strunz No: 09.BG.15





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