Chromdravite Mineral Data

Chromdravite Mineral Data
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General Chromdravite Information

Help on Chemical Formula: Chemical Formula: NaMg3(Cr,Fe+++)6(BO3)3Si6O18(OH)4
Help on Composition: Composition: Molecular Weight = 1,114.61 gm
   Sodium      2.06 %  Na    2.78 % Na2O
   Magnesium   6.54 %  Mg   10.85 % MgO
   Chromium   20.99 %  Cr   27.45 % CrO
   Iron        7.52 %  Fe   10.75 % Fe2O3
   Silicon    15.12 %  Si   32.34 % SiO2
   Boron       2.91 %  B     9.37 % B2O3
   Hydrogen    0.36 %  H     3.23 % H2O
   Oxygen     44.50 %  O
             ______        ______ 
             100.00 %       96.77 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: NaMg3Cr4.5Fe3+1.5(BO3)3Si6O18(OH)4
Help on Environment: Environment: Magnesium and chromium-bearing tourmaline in micaceous metasomatites.
Help on IMA Status: IMA Status: Approved IMA 1983 (Dana # Changed)
Help on Locality: Locality: Onezhkii depression, central Karelia, Russia. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the compositional relationship to dravite.
Help on Synonym: Synonym: Chromdravite - (61.3.1.11)
  Tourmaline
 

Chromdravite Image

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Chromdravite

Comments: Dark green chromdravite grains in matrix.
Location: Srednyaya Padma U-V deposit, Zaonezhie peninsula, Lake Onega, Karelia Republic, Northern Region, Russia. Scale: Specimen Size 2 cm.
© Jeff Weissman / Photographic Guide to Mineral Species

Chromdravite Crystallography
Help on Axial Ratios: Axial Ratios: a:c = 1:0.45127
Help on Cell Dimensions: Cell Dimensions: a = 16.11, c = 7.27, Z = 3; V = 1,634.02 Den(Calc)= 3.40
Help on Crystal System: Crystal System: Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: R 3m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.62(1), 3.04(0.75), 3.58(0.75),
Click Here for Large Chromdravite Structure Window Crystal Structure:

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Bosi F , Lucchesi S , Reznitskii L , European Journal of Mineralogy , 16 (2004) p.345-352, Crystal chemistry of the dravite-chromdravite series, Note: Tourmaline TMt3b, Locality: Sludyanka crystalline complex, Lake Baikal, Russia

View Additional jPOWD Structure files for Chromdravite
[1] [2] [3]
 

Physical Properties of Chromdravite

Help on Cleavage: Cleavage: None
Help on Color: Color: Greenish black, Dark green.
Help on Density: Density: 3.4
Help on Diaphaneity: Diaphaneity: Translucent to Opaque
Help on Habit: Habit: Blocky - Crystal shape tends to be equant (e.g. feldspars).
Help on Habit: Habit: Striated - Parallel lines on crystal surface or cleavage face.
Help on Hardness: Hardness: 7-7.5 - Quartz-Garnet
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous - Resinous
Help on Streak: Streak: greenish gray
 

Optical Properties of Chromdravite

Help on Dichroism (e): Dichroism (e): yellow green.
Help on Dichroism (w): Dichroism (w): dark green.
Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.029 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.029 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2209,KPDmeas= 0.2209,KC= 0.2147
Ncalc = 1.73
Help on Optical Data: Optical Data: Uniaxial (-), e=1.722-1.724, w=1.778-1.78, bire=0.0560.
 

Calculated Properties of Chromdravite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.32 gm/cc
note: Specific Gravity of Chromdravite =3.40 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.04
Boson Index = 0.96
Help on Photoelectric: Photoelectric: PEChromdravite = 7.71 barns/electron
U=PEChromdravite x rElectron Density= 25.62 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Chromdravite is Not Radioactive
 

Chromdravite Classification
Help on Dana Class: Dana Class: 61.03e.01.11 (61)Cyclosilicate Six-Membered Rings
  (61.03e)with borate groups (Sodic Tourmaline Subgroup)
  (61.03e.01)Schorl Subgroup
 
61.03e.01.09 Dravite! NaMg3Al6(BO3)3Si6O18(OH)4 R 3m 3m
 
61.03e.01.10 Schorl! NaFe3Al6(BO3)3Si6O18(OH)4 R 3m 3m
 
61.03e.01.10a Schorl-(F)! NaFe3Al6Si6O18)(BO3)3(OH)3(F,OH) R 3m 3m
 
61.03e.01.11 Chromdravite! NaMg3(Cr,Fe)6(BO3)3Si6O18(OH)4 R 3m 3m
 
61.03e.01.12 Vanadiumdravite! NaMg3V6(Si6O18)(BO3)3(OH)4 R 3m 3m
Help on Strunz Class: Strunz Class: 09.CK.05 09 - SILICATES (Germanates)
  09.C - Cyclosilicates
  09.CK -[Si6O18]12- 6-membered single rings, with insular complex anions
 
09.CK.05 Chromdravite! NaMg3(Cr,Fe)6(BO3)3Si6O18(OH)4 R 3m 3m
 
09.CK.05 Feruvite! (Ca,Na)(Fe,Mg,Ti)3(Al,Mg,Fe)6(BO3)3Si6O18(OH)4 R 3m 3m
 
09.CK.05 Dravite NaMg3Al6(BO3)3Si6O18(OH)4 R 3m 3m
 
09.CK.05 Buergerite! NaFe3Al6(BO3)3Si6O21F R 3m 3m
 
09.CK.05 Foitite! []Na<0.5(Fe,Al)3Al6Si6O18(BO3)3(OH)4 R 3m 3m
 
09.CK.05 Liddicoatite! Ca(Li,Al)3Al6(BO3)3Si6O18(O,OH,F)4 R 3m 3m
 
09.CK.05 Elbaite Na(Li,Al)3Al6(BO3)3Si6O18(OH)4 R 3m 3m
 
09.CK.05 Rossmanite! []LiAl2Al6(Si6O18)(BO3)3(OH)4 R 3m 3m
 
09.CK.05 Olenite! NaAl3Al6(BO3)3(Si6O18)(O,OH)4 R 3m 3m
 
09.CK.05 Povondraite! (Na,K)(Fe,Fe)3(Fe,Mg,Al)6(BO3)3Si6O18(OH)4 R 3m 3m
 
09.CK.05 Schorl NaFe3Al6(BO3)3Si6O18(OH)4 R 3m 3m
 
09.CK.05 Uvite (Ca,Na)(Mg,Fe)3Al5Mg(BO3)3Si6O18(OH,F)4 R 3m 3m
 
09.CK.05 Vanadiumdravite! NaMg3V6(Si6O18)(BO3)3(OH)4 R 3m 3m
 
09.CK.05 Magnesiofoitite! [](Mg2Al)Al6(Si6O18)(BO3)3(OH)4 R 3m 3m
 
09.CK.05 Hydroxyuvite! CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH) R 3m 3m
 
09.CK.05 Schorl-(F)! NaFe3Al6Si6O18)(BO3)3(OH)3(F,OH) R 3m 3m
 

Other Chromdravite Information
Help on References: References: NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)
Help on See Also: See Also: Links to other databases for Chromdravite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineral and Gemstone Kingdom
13 - Mineralienatlas (Deutsch)
14 - QUT Mineral Atlas
15 - Ruff.Info

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Chromdravite

NaMg3(Cr,Fe+++)6(BO3)3Si6O18(OH)4
Dana No: 61.03e.01.11 Strunz No: 09.CK.05
Locality:

 

Notes: