Grandidierite Mineral Data

General Grandidierite Information

Chemical Formula:

(Mg,Fe++)Al3(BO4)(SiO4)O

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

Empirical Formula:

Mg_0.75Fe²⁺_0.25Al₃(BO₄)(SiO₄)O

Environment:

Rare accessory mineral in aluminous boron-rich rocks, thermally and high-grade regionally metamorphosed under low pressure; in pegmatites, aplites, gneisses; in xenoliths.

IMA Status:

Valid Species (Pre-IMA) 1902

Locality:

Andrahomana, southwest of Fort Dauphin, southern Madagascar. Link to MinDat.org Location Data.

Name Origin:

Named for Alfred Grandidier (1836-1912), French naturalist and explorer, an authority on Madagascar.

Name Pronunciation:

Grandidierite + Pronunciation

Synonym:

ICSD 36064

PDF 18-581

Grandidierite Image

Images:

Grandidierite

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

Images:

Grandidierite Boralsilite

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

Axial Ratios:

a:b:c =0.9417:1:0.5245

Cell Dimensions:

a = 10.34, b = 10.98, c = 5.76, Z = 4; V = 653.95 Den(Calc)= 3.01

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pbnm

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 5.04(1), 5.17(1), 5.48(0.8),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Stephenson D A , Moore P B , Acta Crystallographica, Section B , 24 (1968) p.1518-1522, The crystal structure of grandidierite, (Mg,Fe)Al3SiBO9, Locality: Fort Dauphin, Madagascar

Physical Properties of Grandidierite

Cleavage:

{100} Good, {010} Good

Color:

Bluish green.

Density:

2.976

Diaphaneity:

Transparent to translucent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

7.5 - Garnet

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Grandidierite

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

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.

Pleochroism (x):

dark bluish green.

Pleochroism (y):

colorless.

Pleochroism (z):

dark green.

Calculated Properties of Grandidierite

Electron Density:

Bulk Density (Electron Density)=2.96 gm/cc
note: Specific Gravity of Grandidierite =3.01 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_{Grandidierite}= 2.74 barns/electron
U=PE_{Grandidierite} x rElectron Density= 8.10 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Grandidierite is Not Radioactive

Grandidierite Classification

Dana Class:

54.01.01.01 (54)Nesosilicate Borosilicates and Some Beryllosilicates

(54.01)with (BO3)

(54.01.01)Grandidierite Group

54.01.01.01 Grandidierite (Mg,Fe)Al3(BO4)(SiO4)O Pbnm 2/m 2/m 2/m

54.01.01.02 Ominelite! (Fe,Mg)Al3BSiO9 Pbnm 2/m 2/m 2/m

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

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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

Search for Grandidierite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Grandidierite :

A Bijoux Google Search for Grandidierite
Adam's Minerals Google Search for Grandidierite
Cape Minerals Google Search for Grandidierite
Dakota Matrix Minerals Google Search for Grandidierite
Excalibur Mineral Corp. Google Search for Grandidierite
Exceptional Minerals Google Search for Grandidierite
John Betts Fine Minerals Search for Grandidierite
McDougall Minerals Google Search for Grandidierite
Mineral News Website Link
Rock and Mineral Shows Google Search for Grandidierite
Weinrich Minerals, Inc. Google Search for Grandidierite

Ask about Grandidierite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Grandidierite Specimen Label here :

Grandidierite

(Mg,Fe++)Al3(BO4)(SiO4)O
Dana No: 54.01.01.01 Strunz No: 09.AJ.05
Locality:

Notes: