Mineral - Chrysoberyl
Chrysoberyl
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
BeAl₂O₄
Unit Cell
a=4.43 b=9.42 c=5.48 Z=4
Physical Properties
Hardness
8.5
Streak
white
Density
Heavy (3,5-6)
Cleavage
Distinct after {110}, imperfect after {010}, indistinct after {001}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
brownyellowgreenbluevioletcolorless
Birefringence
0.010
Luster
Vitreous,
Greasy
Transparency
translucent,
transparent
Pleochroism
X = Rot
Y = Orange-Gelb
Z = Grün
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pnma (62)
Habit
prismatic, tabular
Formation
Magmatic (pegmatites), Metamorphism, alluvial
Paragenesis
Twinning
Two- to six-count rotational twins after {130}
Rarity
Rather rare
Synonyms
Chrysoberyl
Composition
Elements
Mass
TiO₂
0.55
Al₂O₃
76.34
FeO
3.60
BeO
19.15
USA (Palache et al. 1952)