Mineralogy Database

Grandidierite Mineral Data

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General Grandidierite Information

Help on Chemical  Formula: Chemical Formula: (Mg,Fe++)Al3(BO4)(SiO4)O
Help on Composition: Composition: Molecular Weight = 296.03 gm
   Magnesium   6.16 %  Mg   10.21 % MgO
   Aluminum   27.34 %  Al   51.67 % Al2O3
   Iron        4.72 %  Fe    6.07 % FeO
   Silicon     9.49 %  Si   20.30 % SiO2
   Boron       3.65 %  B    11.76 % B2O3
   Oxygen     48.64 %  O
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Mg0.75Fe2+0.25Al3(BO4)(SiO4)O
Help on Environment: Environment: Rare accessory mineral in aluminous boron-rich rocks, thermally and high-grade regionally metamorphosed under low pressure; in pegmatites, aplites, gneisses; in xenoliths.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1902
Help on Locality: Locality: Andrahomana, southwest of Fort Dauphin, southern Madagascar. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Alfred Grandidier (1836-1912), French naturalist and explorer, an authority on Madagascar.
Help on Name Pronunciation: Name Pronunciation: Grandidierite + Pronunciation Say GRANDIDIERITE
Help on Synonym: Synonym: ICSD 36064
  PDF 18-581

Grandidierite Image

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Comments: Translucent blue-green crystalline grandidierite in pegmatite.
Location: Vohibola, Madagascar. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

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  Boralsilite   Grandidierite

Comments: B&W PPL image of aggregates of boralsilite in quartz near grandidierite. Pyrite is partially replaced by oxide. Abbrev: A+B = Secondary andalusite, B = boralsilite, G = grandidierite, P = pyrite, Q = quartz. (AmMin v93:294).
Location: Pegmatites from the Larsemann Hills, East Antarctica. Scale: See Image.
© American Mineralogist

Grandidierite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.9417:1:0.5245
Help on Cell Dimensions: Cell Dimensions: a = 10.34, b = 10.98, c = 5.76, Z = 4; V = 653.95 Den(Calc)= 3.01
Help on Crystal System: Crystal System: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pbnm
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 5.04(1), 5.17(1), 5.48(0.8),

Physical Properties of Grandidierite

Help on Cleavage: Cleavage: {100} Good, {010} Good
Help on Color: Color: Bluish green.
Help on Density: Density: 2.976
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Brittle - Uneven - Very brittle fracture producing uneven fragments.
Help on Habit: Habit: Tabular - Form dimensions are thin in one direction.
Help on Hardness: Hardness: 7.5 - Garnet
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Grandidierite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.019 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.008 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2079,KPDmeas= 0.2102,KC= 0.2063
Ncalc = 1.61 - 1.62
Help on Optical Data: Optical Data: Biaxial (-), a=1.602, b=1.636, g=1.639, bire=0.0370, 2V(Calc)=32, 2V(Meas)=24-32. Dispersion strong, r < v.
Help on Pleochroism (x): Pleochroism (x): dark bluish green.
Help on Pleochroism (y): Pleochroism (y): colorless.
Help on Pleochroism (z): Pleochroism (z): dark green.

Calculated Properties of Grandidierite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.96 gm/cc
note: Specific Gravity of Grandidierite =3.01 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEGrandidierite = 2.74 barns/electron
U=PEGrandidierite x rElectron Density= 8.10 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Grandidierite is Not Radioactive

Grandidierite Classification

Help on  Dana Class: Dana Class: (54)Nesosilicate Borosilicates and Some Beryllosilicates
  (54.01)with (BO3)
  (54.01.01)Grandidierite Group Grandidierite (Mg,Fe)Al3(BO4)(SiO4)O Pbnm 2/m 2/m 2/m Ominelite! (Fe,Mg)Al3BSiO9 Pbnm 2/m 2/m 2/m
Help on  Strunz Class: Strunz Class: 09.AJ.05 09 - SILICATES (Germanates)
  09.A - Nesosilicates
  09.AJ -Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra,
09.AJ.05 Grandidierite (Mg,Fe)Al3(BO4)(SiO4)O Pbnm 2/m 2/m 2/m
09.AJ.05 Ominelite! (Fe,Mg)Al3BSiO9 Pbnm 2/m 2/m 2/m

Other Grandidierite Information

Help on References: References: NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)
Help on See Also: See Also: Links to other databases for Grandidierite :
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.AJ.05





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