Bertrandite Mineral Data

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General Bertrandite Information

Chemical Formula:

Be4Si2O7(OH)2

Composition:

Molecular Weight = 238.23 gm

Beryllium 15.13 % Be 42.00 % BeO

Silicon 23.58 % Si 50.44 % SiO₂

Hydrogen 0.85 % H 7.56 % H₂O

Oxygen 60.44 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Be₄(Si₂O₇)(OH)₂

Environment:

Commonly found in Be-bearing pegmatites and may be derived from the alteration of beryl.

IMA Status:

Valid Species (Pre-IMA) 1883

Locality:

Discovered at near Nantes, Loire-Inferieure, France. Also found at Irkutka and Altai Mountains, Siberia, Russia. Link to MinDat.org Location Data.

Name Origin:

Named after the French mineralogist, E. Bertrand.

Name Pronunciation:

Bertrandite + Pronunciation

Synonym:

ICSD 202360

PDF 24-509

Bertrandite Image

Images:

Bertrandite

Comments: Colorless prismatic crystals of bertrandite on matrix with pale pink rhombohedral crystals of rhodochrosite.
Location: Yiaoguanshen mine, Hunan Province, China. Scale: 3.5 x 4 cm.
© Dan Weinrich

Images:

Bertrandite

Comments: Fan-like clusters of bertrandite crystals with brown rhodochrosite and quartz.
Location: Kara Oba, Kazakhstan. Scale: Crystal size 1.1 cm.
© John Veevaert

Bertrandite Crystallography

Axial Ratios:

a:b:c =1.7514:1:0.5224

Cell Dimensions:

a = 15.22, b = 8.69, c = 4.54, Z = 4; V = 600.47 Den(Calc)= 2.64

Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: Ccm21

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

By Intensity(I/I_o): 4.38(1), 3.19(0.9), 2.54(0.8),

Crystal Structure:

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Downs J W , Ross F K , American Mineralogist , 72 (1987) p.979-983, Neutron-diffraction study of bertrandite, Note: O2y has been corrected

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

Physical Properties of Bertrandite

Cleavage:

{001} Perfect, {110} Distinct, {101} Distinct

Color:

Colorless, Pale yellow.

Density:

2.59 - 2.6, Average = 2.59

Diaphaneity:

Translucent to transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

6-7 - Orthoclase-Quartz

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Bertrandite

Gladstone-Dale:

CI meas= -0.005 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.012 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2285,KPDmeas= 0.2325,KC= 0.2314
Ncalc = 1.6 - 1.61

Optical Data:

Biaxial (-), a=1.591, b=1.605, g=1.614, bire=0.0230, 2V(Calc)=76, 2V(Meas)=73-81. Dispersion none.

Pleochroism (x):

none.

Pleochroism (y):

none.

Pleochroism (z):

none.

Calculated Properties of Bertrandite

Electron Density:

Bulk Density (Electron Density)=2.57 gm/cc
note: Specific Gravity of Bertrandite =2.60 gm/cc.

Fermion Index:

Fermion Index = 0.16
Boson Index = 0.84

Photoelectric:

PE_Bertrandite= 1.07 barns/electron
U=PE_Bertrandite x rElectron Density= 2.75 barns/cc.

Radioactivity:

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

Bertrandite Classification

Dana Class:

56.01.01.01 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.01)with cations in [4] coordination

(56.01.01)Dana Group

56.01.01.01 Bertrandite Be4Si2O7(OH)2 Ccm21 mm2

Strunz Class:

09.BD.05 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BD -Si2O7 groups with additional anions;

09.BD.05 Bertrandite Be4Si2O7(OH)2 Ccm21 mm2

Other Bertrandite Information

References:

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

See Also:

Links to other databases for Bertrandite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info
16 - Scandinavian mineral gallery
17 - WWW-MINCRYST

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

Bertrandite

Be4Si2O7(OH)2
Dana No: 56.01.01.01 Strunz No: 09.BD.05
Locality:

Notes: