Alexandrite
Variety BeAl2O4
About it
Chrysoberyl that looks green in daylight and red under warm incandescent light, thanks to chromium. First found in the Ural Mountains of Russia; Sri Lanka, Brazil, and East Africa supply most today.
- Type
- Variety
- Group
- Chrysoberyl variety
- Formula
- BeAl2O4
- Hardness (Mohs)
- 8.5
- Specific gravity
- 3.7–3.78
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Orthorhombic
- Colours
- green or bluish green in daylight, red to purplish red in incandescent light
- Transparency
- transparent
- Cleavage and fracture
- distinct prismatic; conchoidal to uneven fracture
- Under UV light
- often weak red under UV
Typical values: real specimens vary. For more, see mindat.org.