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Chrysoberyl

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Formula:
BeAl2O4
System:
Orthorhombic
Colour:
Green shades, ...
Lustre:
Vitreous
Hardness:
Name:
From the Greek χρυσός, golden, and βήρυλλος, beryl, in allusion to the color.
The green (chromium-bearing) gem variety, that shows a colour change under different light sources, is called alexandrite.

The Cr-analogue is called mariinskite.

Visit gemdat.org for gemological information about Chrysoberyl.

Classification of Chrysoberyl

Approved
4.BA.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
A : With small and medium-sized cations
7.2.9.1

7 : MULTIPLE OXIDES
2 : AB2X4
7.4.4

7 : Oxides and Hydroxides
4 : Oxides of Be, Mg and the alkaline earths
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First Recorded Occurrence of Chrysoberyl

Year of Discovery:
1789

Occurrences of Chrysoberyl

Geological Setting:
Granite pegmatites.

Physical Properties of Chrysoberyl

Vitreous
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Green shades, emerald-green, greenish white, yellowish green, greenish brown, yellow, blue
Streak:
White
Hardness (Mohs):
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {110}, imperfect on {010}, poor on (001)
Fracture:
Irregular/Uneven, Conchoidal
Density:
3.75(1) g/cm3 (Measured)    3.69 g/cm3 (Calculated)

Crystallography of Chrysoberyl

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 5.481Å, b = 9.415Å, c = 4.428Å
Ratio:
a:b:c = 0.582 : 1 : 0.47
Unit Cell Volume:
V 228.50 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Simple crystals usually tabular {001}; short prismatic [100] at times, or, less often, [001]. Striated on {001} parallel to [100]. Twinned crystals usually flattened perpendicular to the composition plane, and have a feather-like striation on {001}. Twinning forms six-rayed spokelike aggregates.
Twinning:
Common on twin plane {130}. Both contact and penetration twins, freqently repeated and forming pseudohexagonal crystals as viewed along [001] with or without reentrant angles. Also flattened heart-shaped

Crystallographic forms of Chrysoberyl

Crystal Atlas:
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Chrysoberyl no.11 - Goldschmidt (1913-1926)
Chrysoberyl no.35 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Chrysoberyl

Type:
Biaxial (+)
RI values:
nα = 1.746 nβ = 1.748 nγ = 1.756
2V:
Measured: 70° , Calculated: 72°
Max Birefringence:
δ = 0.010
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v
Pleochroism:
Visible
Comments:
X = c = columbine-red
Y = b = orange-yellow
Z = a = emerald-green
Comments:
Exhibits a bluish opalescence or chatoyancy, notably on {010}. Also asteriated with a cat's eye effect.

Chemical Properties of Chrysoberyl

Formula:
BeAl2O4
Essential elements:
All elements listed in formula:
Common Impurities:
Fe,Cr,Ti

Relationship of Chrysoberyl to other Species

7.4.1BromelliteBeO
7.4.2BehoiteBe(OH)2
7.4.3ClinobehoiteBe(OH)2
7.4.5Magnesiotaaffeite-2N’2SMg3Al8BeO16
7.4.6Magnesiotaaffeite-6N’3SMg2BeAl6O12
7.4.7PericlaseMgO
7.4.8BruciteMg(OH)2
7.4.9SpinelMgAl2O4
7.4.10MeixneriteMg6Al2(OH)16(OH)2 · 4H2O
7.4.11LimeCaO
7.4.12PortlanditeCa(OH)2
7.4.13ChlormayeniteCa12Al14O32Cl2
7.4.14HydrocalumiteCa4Al2(OH)12(Cl,CO3,OH)2 · 4H2O
7.4.15MarokiteCaMn23+O4
7.4.16Ranciéite(Ca,Mn)Mn4O9 · 3H2O
7.4.17HollanditeBa(Mn64+Mn23+)O16
7.4.18Romanèchite(Ba,H2O)2Mn5O10
7.4.19Todorokite(Ca,K,Na,Mg,Ba,Mn)(Mn,Mg,Al)6O12 · 3H2O

Other Names for Chrysoberyl

Name in Other Languages:

Other Information

Electrical:
Electrical conductivity increases with temperature.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Chrysoberyl

Reference List:
Werner (1789), Bergm. Journal: 373, 387 (as Krisoberil).

Haüy (1798): 4: 5 (as Cymophane).

Des Cloizeaux (1845), Ann. chim. phys.:(3): 13.

Melczer (1900), Zs. Kr.: 33: 246.

Gldschmidt (1913): 2: 154.

Adams and Graham (1926), Royal Society of Canada, Transactions: (3) sec. 4: 20: 113.

Bragg and Brown (1926), Zs. Kr.: 63: 122.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 718-722.

American Mineralogist (1963): 48: 804-810.

Internet Links for Chrysoberyl

Specimens:
The following Chrysoberyl specimens are currently listed for sale on minfind.com.

Localities for Chrysoberyl

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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