Macfallite Mineral Data + Say MACFALLITE

General Macfallite Information

Help on Chemical  Formula: Chemical Formula: Ca2(Mn+++,Al)3(SiO4)(Si2O7)(OH)3
Help on Composition: Composition: Molecular Weight = 542.26 gm
   Calcium    14.78 %  Ca   20.68 % CaO
   Manganese  25.33 %  Mn   36.39 % Mn2O3
   Aluminum    2.49 %  Al    4.70 % Al2O3
   Silicon    15.54 %  Si   33.24 % SiO2
   Hydrogen    0.56 %  H     4.98 % H2O
   Oxygen     41.31 %  O
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ca2Mn3+2.5Al0.5(SiO4)(Si2O7)(OH)3
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 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 =1.6817:1:1.4738
Help on Cell Dimensions: Cell Dimensions: a = 10.235, b = 6.086, c = 8.97, Z = 2; beta = 110.75° V = 522.50 Den(Calc)= 3.45
Help on Crystal System: Crystal System: Monoclinic - PrismaticH-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),
Click Here for Large Macfallite Structure Window Crystal Structure:

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Moore P B , Shen J , Araki T , American Mineralogist , 70 (1985) p.171-181, Crystal chemistry of the (M2)3+ phi2 sheet: Structural principles and crystal, structures of ruizite, macfallite and orientite

 

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= 0.075 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2301,KPDmeas= 0.2314,KC= 0.2488
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:

relectron=3.37 gm/cc
note: rMacfallite =3.43 gm/cc.

Help on Fermion Index Fermion Index Fermion Index = 0.00765
Boson Index = 0.99235
Help on Photoelectric: Photoelectric:

PEMacfallite = 8.92 barns/electron
U=PEMacfallite x relectron= 30.03 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: 58.2.3.2 (58)Sorosilicate Insular, Mixed, Single, and Larger Tetrahedral Groups
  (58.2)with cations in [6] and higher coordination; single and double groups (n=1,2)
  (58.2.3)Sursassite and related species
 
58.2.3.1 Sursassite Mn2Al3(SiO4)(Si2O7)(OH)3 P 21/m 2/m
 
58.2.3.2 Macfallite Ca2(Mn,Al)3(SiO4)(Si2O7)(OH)3 P 21/m 2/m
Help on  Strunz Class: Strunz Class: VIII/C.24-10 VIII - Silicates
  VIII/C - Sorosilicates, mixed structure with [SiO4]2- "inseln" and [Si2O7]6- groups
  VIII/C.24 - Pumpellyite group
 
VIII/C.24-10 Macfallite Ca2(Mn,Al)3(SiO4)(Si2O7)(OH)3 P 21/m 2/m
 
VIII/C.24-20 Sursassite Mn2Al3(SiO4)(Si2O7)(OH)3 P 21/m 2/m
 
VIII/C.24-30 Pumpellyite-(Mg) Ca2MgAl2(SiO4)(Si2O7)(OH)2·(H2O) A2/m 2/m
 
VIII/C.24-40 Pumpellyite-(Fe++) Ca2Fe(Al,Fe)2(SiO4)(Si2O7)(OH)2·(H2O) A2/m 2/m
 
VIII/C.24-42 Pumpellyite-(Fe+++) Ca2FeAl2(SiO4)(Si2O7)(OH,O)2·(H2O) A2/m 2/m
 
VIII/C.24-50 Pumpellyite-(Mn++) Ca2(Mn,Mg)(Al,Mn,Fe)2(SiO4)(Si2O7(OH)2·(H2O) A2/m 2/m
 
VIII/C.24-60 Julgoldite-(Fe++) Ca2Fe(Fe,Al)2(SiO4)(Si2O7)(OH)2·(H2O) C 2/m 2/m
 
VIII/C.24-61 Julgoldite-(Fe+++) Ca2Fe(Fe,Al)2(SiO4)(Si2O7)(O,OH)2·(H2O) A2/m 2/m
 
VIII/C.24-70 Shuiskite Ca2(Mg,Al)(Cr,Al)2(SiO4)(Si2O7)(OH)2·(H2O) A2/m 2/m
 
VIII/C.24-80 Okhotskite-(Mg)* Ca3(Mg,Mn)(Mn,Al,Fe)(SiO4)(Si2O7)(OH)2·(H2O) Mono
 
VIII/C.24-80* Okhotskite-(Mn++) Ca2(Mn,Mg)(Mn,Al,Fe)Si3O10(OH)4 A2/m 2/m
 
VIII/C.24-90 Samfowlerite Ca14Mn3Zn2(Be,Zn)2Be6(SiO4)6(Si2O7)4(OH,F)6 P 21/c 2/m
 

Other Macfallite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Dana8) 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 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (MinSocAm) 7 -Handbook of Mineralogy (UofA) 8 -MinDAT 9 -MinMax(Deutsch) 10 -MinMax(English) 11 -Mineralienatlas (Deutsch) 12 -QUT Mineral Atlas 13 - WWW-MINCRYST 14 -École des Mines de Paris

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Macfallite

Ca2(Mn+++,Al)3(SiO4)(Si2O7)(OH)3
Dana No: 58.2.3.2 Strunz No: VIII/C.24-10
Locality:

 

Notes:

 

 
   
 
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