What is "serendibite"

n. (context mineralogy English) A triclinic-pinacoidal mineral containing aluminum, boron, calcium, magnesium, oxygen, and silicon.

Serendibite is an extremely rare mineral and gem that was first discovered in 1902 in Sri Lanka by Dunil Palitha Gunasekera and named after Serendib, the old Arabic name for Sri Lanka. It is considered one of the rarest gemstones in the world.