Large painite crystal on white background — Photo: Mineral Enthusiast · CC BY-SA 4.0
Painite
A calcium-zirconium-boron-aluminium borate once called the world's rarest gemstone — first misidentified as ruby in Myanmar.
Intro adapted from Wikipedia (CC BY-SA).
Painite is an IMA-recognized mineral species in the borate class, with the chemical formula CaZrAl₉O₁₅(BO₃).
It crystallizes in the hexagonal crystal system (space group P6_3/m).
Key properties: Mohs hardness 8; specific gravity 4.01–4.03; typically brown or red or black; white streak; vitreous luster; refractive index 1.802; optically uniaxial.
IMA symbol Pai, grandfathered status — known before the IMA’s founding, named in 1957.
Found in gem gravels.
It is found associated with Corundum, phlogopite.
The name refers to Arthur Charles Davy Pain (1901-1971), British gem collector, who first noted the species.
Collections: Gemstones, Rare & Remarkable.