Alexandrite
Variety of chrysoberyl
Very Rare · BeAl₂O₄
Chromium-bearing chrysoberyl that looks green in daylight and raspberry red under incandescent light: chromium absorbs the middle of the spectrum and lets both green and red through, and the light source tips the balance. First found in the emerald mines of the Ural Mountains in 1830 and named after the future Tsar Alexander II.
Identity
- Formula
- BeAl₂O₄
- Chemical class
- Oxide
- Also known as
- Color-change chrysoberyl
Crystallography
- Crystal system
- Orthorhombic
- Habits
- Tabular, Prismatic
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 8.5
- Density
- 3.73 g/cm³
- Luster
- Vitreous
- Colors
- green, blue-green, red, purple
- Streak
- white
- Transparency
- Transparent, Translucent
Geology
- Origins
- Metamorphic, Igneous
- Host rocks
- Granite, Schist and gneiss, River gravels and sands
- Associated minerals
- Beryl, Phenakite, Mica, Tourmaline
- Found in
- Pegmatite deposit, Placer deposit
- Geography
- Russia (Ural Mountains), Brazil, Sri Lanka, Tanzania, India
Classification
- Rarity
- Very Rare
- Gem quality
- Yes
Arcane properties
- Affinity
- Arcane, Time
- Effects
- Illusion, Time
- Planar origin
- Material Plane
Sources
- Alexandrite. Mindat.org (Hudson Institute of Mineralogy).
- Chrysoberyl. Mindat.org (Hudson Institute of Mineralogy).
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Chrysoberyl. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Alexandrite. Gemdat.org (Hudson Institute of Mineralogy).
- Alexandrite History and Lore. Gemological Institute of America, Gem Encyclopedia.
Browse the Crystal Encyclopedia — MGS Toolbox