Sinhalite
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Description
A transparent to translucent gem-quality stone that is a borate mineral with formula MgAl(BO4). Sinhalite was traded as Peridot from Sri Lanka until 1952 when it was recognized as a unique composition by mineralogists at the British Museum. Sinhalite is usually a greenish to brownish yellow, but may also be found in white, gray, pink, brown colors. Gem quality crystals have been found in Sri Lanka, Madagascar, Tanzania, and Myanmar (Burma).
Physical and Chemical Properties
- Orthorhombic crystal system
- Fracture = conchoidal
- Luster = vitreous
- Streak = white
- Fluorescence = inert
- Pleochroism = moderate: light brown, dark brown, and greenish brown
| Mohs Hardness | 6.5 - 7.0 |
|---|---|
| Density | 3.475 - 3.500 g/ml |
| Refractive Index | 1.668 - 1.707 |
| Birefringence | 0.036 - 0.039 |
Resources and Citations
- Gem Identification Lab Manual, Gemological Institute of America, 2016.
- R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
- Wikipedia: Sinhalite June 2022 and Dec 2022.