Chrysoberyl Mineral Data

General Chrysoberyl Information

Chemical Formula:

BeAl2O4

Composition:

Molecular Weight = 126.97 gm

Beryllium 7.10 % Be 19.70 % BeO

Aluminum 42.50 % Al 80.30 % Al₂O₃

Oxygen 50.40 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

BeAl₂O₄

Environment:

Granitic pegmatite dikes.

IMA Status:

Valid Species (Pre-IMA) 1790

Locality:

Takowaja, Russia. Link to MinDat.org Location Data.

Name Origin:

From the Greek chrysos - "golden" and the mineral beryl.

Name Pronunciation:

Chrysoberyl + Pronunciation

Synonym:

Alexandrite - green

ICSD 62501

PDF 11-448

Chrysoberyl Image

Images:

Chrysoberyl

Comments: Chrysoberyl (alexandrite) sixling twin crystal.
Location: Zimbabwe. Scale: Crystal size 2.3 cm.
© Richard Dale / Dale Minerals

Images:

Chrysoberyl

Comments: Chrysoberyl (Alexandrite) crystal on matrix with excellent color change (Daylight, Tungsten Bulb).
Location: Malyshevo, Yekaterina Oblast', Urals, Russia. Scale: Crystal size 1.2 cm.
© Kevin Ward

Chrysoberyl Crystallography

Axial Ratios:

a:b:c =0.5823:1:0.4707

Cell Dimensions:

a = 5.476, b = 9.404, c = 4.427, Z = 4; V = 227.97 Den(Calc)= 3.70

Crystal System:

Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pmnb

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

By Intensity(I/I_o): 3.24(1), 2.091(0.9), 1.619(0.8),

Forms:

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Forms: ( 0 1 0) ( 1 2 1) ( 0 1 1) ( 1 1 1) ( 1 1 0) ( 1 0 0)

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Physical Properties of Chrysoberyl

Cleavage:

{110} Distinct, {010} Imperfect, {???} Imperfect

Color:

Blue green, Brown, Brownish green, Green, Gray.

Density:

3.5 - 3.84, Average = 3.67

Diaphaneity:

Transparent to translucent

Fracture:

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

Habit:

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

Habit:

Tabular - Form dimensions are thin in one direction.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

8.5 - Chrysoberyl

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Chrysoberyl

Gladstone-Dale:

CI meas= 0.044 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.052 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2024,KPDmeas= 0.2041,KC= 0.2135
Ncalc = 1.75 - 1.82

Optical Data:

Biaxial (+), a=1.745, b=1.748, g=1.754, bire=0.0090, 2V(Calc)=72, 2V(Meas)=45. Dispersion none.

Pleochroism (x):

none.

Calculated Properties of Chrysoberyl

Electron Density:

Bulk Density (Electron Density)=3.58 gm/cc
note: Specific Gravity of Chrysoberyl =3.67 gm/cc.

Fermion Index:

Fermion Index = 0.07
Boson Index = 0.93

Photoelectric:

PE_Chrysoberyl= 1.31 barns/electron
U=PE_Chrysoberyl x rElectron Density= 4.68 barns/cc.

Radioactivity:

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

Chrysoberyl Classification

Dana Class:

07.02.09.01 (07)Multiple Oxides

(07.02)(A+ B++)2 X4 Spinel group

(07.02.09)Dana Group

07.02.09.01 Chrysoberyl BeAl2O4 Pmnb 2/m 2/m 2/m

Strunz Class:

04.BA.05 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.B - Metal:Oxygen = 3:4 and similar

04.BA -With small and medium-sized cations

04.BA.05 Chrysoberyl BeAl2O4 Pmnb 2/m 2/m 2/m

Other Chrysoberyl Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Mason68)

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Chrysoberyl

BeAl2O4
Dana No: 07.02.09.01 Strunz No: 04.BA.05
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Notes:

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