Earth Treasures: Sinhalite

By Chisom Ibemere

Sinhalite is a rare magnesium aluminum borate mineral that was first discovered in Sri Lanka in the early 1900s, where it was named after the Sinhalese people who live on the island. It is typically found in metamorphic rocks such as marble and skarn deposits, as well as in volcanic rocks such as basalt.

Sinhalite has a hardness of 6.5-7 on the Mohs scale, a specific gravity of 3.4-3.6, and a vitreous to resinous lustre. It is typically colourless to pale yellow, pink, or brown, with a conchoidal fracture and no cleavage. Sinhalite is also fluorescent under ultraviolet light.

Sinhalite has several uses, although it is mainly valued as a rare and beautiful gemstone. It is faceted into small, brilliant stones that display strong birefringence, making them appear to have a doubling effect. Sinhalite is also used in the manufacture of ceramics, glass, and other materials due to its high melting point and resistance to chemical corrosion. Finally, sinhalite is sometimes used as a minor ore of magnesium and aluminum in some industrial applications.

Sinhalite has only been reported from a limited number of locations worldwide, including Sri Lanka (where it was first discovered), Myanmar, Tanzania, Madagascar, and the United States. It is a relatively rare and lesser-known gemstone, which may not be as valuable as other gemstones such as diamonds, rubies, or emeralds.

High-quality Sinhalite gemstones can command prices of several hundred dollars per carat, particularly in the collector’s market. The industrial value of Sinhalite is also low, as it is not a major source of magnesium or aluminum.

Sinhalite can be found in association with other gem gravel minerals including peridot, garnet, ruby, and sapphire. Large specimens are rare, but do exist.