SINHALITE: Sri Lanka (4.58, 7.07 // 4.18,9.18)
Long thought to be brown peridot, sinhalite was investigated in 1952 and found to be a new mineral. When cut, it is richly colored, bright, and attractive, and resembles citrine, peridot, or zircon. Large gems are very rare, but smaller stones are available in the marketplace. Some people have reported that it was easier at times to find a large sinhalite for sale than a small one, however, as rough pebbles from Sri Lanka are often large.
Sinhalite Value
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Sinhalite Information
| Data | Value |
| Name | Sinhalite |
| Crystallography | Orthorhombic; found only as grains and rolled pebbles. |
| Colors | Yellowish, yellow-brown, dark brown, greenish brown, light pink, brownish pink. |
| Luster | Vitreous. |
| Hardness | 6.5-7. |
| Density | 3.475—3.50. |
| Birefringence | 0.035—0.037. |
| Cleavage | Not determined. |
| Stone Sizes | Interestingly, sinhalite, though quite rare, occurs in large sizes in the Sri Lankan gravels. The normal range is 1-20 carats, but gems over 100 carats have been found from time to time. Smithsonian Institution (Washington, D.C): 109.8 (brown, Sri Lanka); 43.5. 36.4 (brown, Sn Lanka). Private Collection: 158 (Sri Lanka)—this is the largest known sinhalite gem. Devonian Group (Calgary, Alberta, Canada): 24.76 (Sri Lanka). National Museums of Canada (Ottawa, Ontario): 21.99 (light brown, Sri Lanka). |
| Luminescence | None. |
| Spectral | Very distinctive; similar to but distinct from peridot: bands at 4930. 4750. 4630 (absent in peridot), 4520 and 4350; general absorption of the violet end of the spectrum. |
| Formula | MgAlBO4. |
| Pleochroism | Distinct: pale brown/greenish brown/dark brown. |
Optics: a=1.665- 1.676; β= 1.697; γ= 1.705-1.712. (Sri Lanka =1.669/1.702/1.706).
Biaxial (-), 2V= 56°.
Occurrence: A contact metamorphic mineral in limestories at granite contacts; alluvial.
Warren County, New York: no gem value.
Northeast Tanzania (in a skarn): pink to brownish pink, some gemmy areas.
Burma: one rolled pebble noted.
Sri Lanka: major source of gem sinhalite. as rolled pebbles in gem gravels.
Comments: Long thought to be brown peridot, sinhalite was investigated in 1952 and found to be a new mineral. When cut, it is richly colored, bright, and attractive, and resembles citrine, peridot, or zircon. Large gems are very rare, but smaller stones are available in the marketplace. Some people have reported that it was easier at times to find a large sinhalite for sale than a small one, however, as rough pebbles from Sri Lanka are often large.
Name: From the old Sanskrit word for Ceylon (now Sri Lanka), sinhala.
