trigonal Oxides
Padparadscha Sapphire (Bipyramidal)
Formula Al2O3
Crystal Structure
#! Species: Padparadscha Sapphire
#! System: Trigonal (-3m)
#! Habit: Bipyramidal with minor basal pinacoid
trigonal[-3m]:{10-11}@1.0 + {0001}@0.4
trigonal
-3m
{10-11} {0001}
Quick Facts
Hardness
9.0
Specific Gravity
3.99
Refractive Index
1.762
Optical Character
Uniaxial -
Physical Properties
- Crystal System
- trigonal
- Hardness (Mohs)
- 9.0
- Specific Gravity
- 3.99
- Cleavage
- None (parting on {0001} and {10-11})
- Fracture
- Conchoidal
- Lustre
- Adamantine to vitreous
Optical Properties
- Refractive Index
- 1.762
- Birefringence
- 0.008
- Optical Character
- Uniaxial -
- Dispersion
- 0.018
- Pleochroism
- moderate: Pinkish-orange / Yellowish-orange
- Fluorescence
- Moderate orange-pink (LWUV)
Characteristics
Colours
Pinkish-orangeOrangish-pinkSalmon pink
Localities
Sri LankaMadagascarTanzaniaMyanmar
Common Inclusions
Silk (rutile needles)FingerprintsCrystalsGrowth zoning
Known Treatments
Heat treatment (common, some lattice diffusion)Beryllium diffusion (controversial)
Crystal Forms
bipyramidpinacoid
Notes
Strict colour definition debated; generally requires both pink and orange components
Related Minerals
Other minerals in the trigonal system
