Sinhalite Value, Price, and Jewelry Information

SINHALITE: Sri Lanka (4.58, 7.07 // 4.18,9.18). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Sinhalite

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 Information

Data Value
Name Sinhalite
Colors Yellowish, yellow-brown, dark brown, greenish brown, light pink, brownish pink.
Crystallography Orthorhombic; found only as grains and rolled pebbles.
Refractive Index 1.665-1.712
Luster Vitreous.
Hardness 6.5-7
Fracture Conchoidal
Specific Gravity 3.475-3.50
Birefringence 0.035-0.037
Cleavage None
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.
Luminescence Present No
Transparency Transparent.
Absorption Spectrum 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°.
Optic Sign Biaxial -

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.

Myanmar: one rolled pebble noted.

Madagascar.

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.

by Joel E. Arem, Ph.D., FGA