General Dravite Information
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Chemical Formula: |
NaMg3Al6(BO3)3Si6O18(OH)4 |
Composition: |
Molecular Weight = 958.75 gm |
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Sodium 2.40 % Na 3.23 % Na2O |
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Magnesium 7.61 % Mg 12.61 % MgO |
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Aluminum 16.89 % Al 31.90 % Al2O3 |
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Silicon 17.58 % Si 37.60 % SiO2 |
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Boron 3.38 % B 10.89 % B2O3 |
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Hydrogen 0.42 % H 3.76 % H2O |
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Oxygen 51.73 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
Empirical Formula: |
NaMg3Al6(BO3)3Si6O18(OH)4 |
Environment: |
Metasomatically altered magnesian or dolomitic limestones in contact-metamorphic aureoles. |
IMA Status: |
Valid Species (Pre-IMA) 1883 (Dana # Changed) |
Locality: |
Drava River, Austria. Link to MinDat.org Location Data. |
Name Origin: |
After its locality. |
Synonym: |
Dravite - (61.3.1.9) |
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ICSD 72937 |
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PDF 44-1457 |
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Tourmaline |
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Dravite Image |
Images:
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Dravite
Comments: Doubly terminated dravite crystal on white mica shist matrix.
Location: Yinnietharra Station, Gascoyne, Western Australia.
Scale: 4 x 4 x 2.9 cm.
© Fabre Minerals |
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Images:
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Dravite
Comments: Greenish-brown chrome-rich dravite tourmaline crystals up to 13 mm long with complex terminations. Fluoresces mildly under UV illumination.
Location: Shako Ranch, Mwatate Kabanga, Voi, Taita-Taveta district, Coast Province, Kenya.
Scale: 14x13x10 mm.
© John Betts - Fine Minerals |
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Dravite Crystallography
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Axial Ratios: |
a:c = 1:0.45172 |
Cell Dimensions: |
a = 15.941, c = 7.201, Z = 3; V = 1,584.73 Den(Calc)= 3.01 |
Crystal System: |
Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: R 3m |
X Ray Diffraction: |
By Intensity(I/Io): 2.576(1), 2.961(0.85), 3.99(0.85), |
Crystal Structure:
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Help on Above
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Hawthorne F C , MacDonald D J , Burns P C , American Mineralogist , 78 (1993) p.265-270, Reassignment of cation site occupancies in tourmaline: Al-Mg disorder in the, crystal structure of dravite
View Additional jPOWD Structure files for Dravite
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[2]
[3]
[4]
[5]
[6]
[7]
[8]
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Physical Properties of Dravite
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Cleavage: |
[???] Indistinct |
Color: |
Black, Green, Red, Blue, White. |
Density: |
2.98 - 3.2, Average = 3.09 |
Diaphaniety: |
Transparent to translucent to opaque |
Fracture: |
Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces. |
Habit: |
Columnar - Forms columns |
Habit: |
Divergent - Crystals radiate from a center without producing stellar forms. |
Habit: |
Massive - Uniformly indistinguishable crystals forming large masses. |
Hardness: |
7-7.5 - Quartz-Garnet |
Luminescence: |
Non-fluorescent. |
Luster: |
Vitreous - Resinous |
Streak: |
colorless |
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Optical Properties of Dravite
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Dichroism (e): |
pale yellow or colorless. |
Dichroism (w): |
dark yellowish brown or light yellow. |
Gladstone-Dale: |
CI meas= 0.034 (Excellent) - where the CI = (1-KPDmeas/KC) CI calc= 0.009 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.21,KPDmeas= 0.2045,KC= 0.2118 |
Optical Data: |
Uniaxial (-), e=1.612-1.63, w=1.631-1.655, bire=0.0190-0.0250. |
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Calculated Properties of Dravite
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Electron Density: |
relectron=2.99 gm/cc note: rDravite =3.01 gm/cc. |
Fermion Index |
Fermion Index = 0.02279 Boson Index = 0.97721 |
Photoelectric: |
PEDravite = 1.42 barns/electron U=PEDravite x relectron= 4.25 barns/cc. |
Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Dravite is Not Radioactive |
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Dravite Classification
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Dana Class: |
61.3e.1.9 (61)Cyclosilicate Six-Membered Rings |
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(61.3e)with borate groups (Sodic Tourmaline Subgroup) |
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(61.3e.1)Dana Group |
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61.3e.1.9 Dravite ! NaMg3Al6(BO3)3Si6O18(OH)4 R 3m 3m |
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61.3e.1.10 Schorl! NaFe3Al6(BO3)3Si6O18(OH)4 R 3m 3m |
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61.3e.1.11 Chromdravite! NaMg3(Cr,Fe)6(BO3)3Si6O18(OH)4 R 3m 3m |
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61.3e.1.12 Vanadiumdravite! NaMg3V6(Si6O18)(BO3)3(OH)4 R 3m 3m |
Strunz Class: |
VIII/E.19-20 VIII - Silicates |
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VIII/E - Cyklosilicates, six rings [Si6O18]12- |
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VIII/E.19 - Tourmaline group |
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VIII/E.19-05 Rossmanite! []LiAl2Al6(Si6O18)(BO3)3(OH)4 R 3m 3m |
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VIII/E.19-10 Elbaite Na(Li,Al)3Al6(BO3)3Si6O18(OH)4 R 3m 3m |
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VIII/E.19-15 Magnesiofoitite! [](Mg2Al)Al6(Si6O18)(BO3)3(OH)4 R 3m 3m |
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VIII/E.19-20 Dravite NaMg3Al6(BO3)3Si6O18(OH)4 R 3m 3m |
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VIII/E.19-30 Chromdravite! NaMg3(Cr,Fe)6(BO3)3Si6O18(OH)4 R 3m 3m |
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VIII/E.19-35 Vanadiumdravite! NaMg3V6(Si6O18)(BO3)3(OH)4 R 3m 3m |
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VIII/E.19-50 Schorl NaFe3Al6(BO3)3Si6O18(OH)4 R 3m 3m |
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VIII/E.19-55 Foitite! []Na<0.5(Fe,Al)3Al6Si6O18(BO3)3(OH)4 R 3m 3m |
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VIII/E.19-60 Olenite! NaAl3Al6(BO3)3(Si6O18)(O,OH)4 R 3m 3m |
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VIII/E.19-70 Buergerite! NaFe3Al6(BO3)3Si6O21F R 3m 3m |
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VIII/E.19-75 Povondraite! (Na,K)(Fe,Fe)3(Fe,Mg,Al)6(BO3)3Si6O18(OH)4 R 3m 3m |
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VIII/E.19-80 Liddicoatite! Ca(Li,Al)3Al6(BO3)3Si6O18(O,OH,F)4 R 3m 3m |
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VIII/E.19-90 Uvite (Ca,Na)(Mg,Fe)3Al5Mg(BO3)3Si6O18(OH,F)4 R 3m 3m |
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VIII/E.19-100 Feruvite! (Ca,Na)(Fe,Mg,Ti)3(Al,Mg,Fe)6(BO3)3Si6O18(OH)4 R 3m 3m |
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Other Dravite Information
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References: |
NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65) |
See Also: |
Links to other databases for Dravite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 -Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 -Athena
6 - CalTech Mineral Spectroscopy
7 - Crocoite.com Mineral Locations
8 - EUROmin Project
9 - Franklin Minerals(Dunn)
10 -Google Images
11 -Google Scholar
12 -Handbook of Mineralogy (MinSocAm)
13 -Handbook of Mineralogy (UofA)
14 - HyperPhysics
15 -MinDAT
16 -MinMax(Deutsch)
17 -MinMax(English)
18 - Mineral and Gemstone Kingdom
19 -Mineralienatlas (Deutsch)
20 -QUT Mineral Atlas
21 - Scandinavian mineral gallery
22 - Tradeshop.com - The Rainbow of Gems
23 - WWW-MINCRYST
24 -École des Mines de Paris
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Dravite
NaMg3Al6(BO3)3Si6O18(OH)4
Dana No: 61.3e.1.9 Strunz No: VIII/E.19-20
Locality:
Notes:
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