Kyawthuite Is So Rare That Only One Specimen Exists in the Whole World

About 50 million years ago, continental drift sent the Indian subcontinent crashing into the Asian continent causing the rise of the Himalayan mountain range. The colossal collision also created a geological environment of heat and pressure perfect for the formation of precious stones, such as rubies, sapphires, jade, spinel, and the rarest of all gemstones, kyawthuite.

Kyawthuite is so rare that only one specimen exists in the whole world. Reddish-orange in color and weighing 1.61 carats, the faceted gem currently resides in the Natural History Museum of Los Angeles County.

The rough kyawthuite crystal was presumed to be amber or topaz when it was discovered in 2010 by sapphire hunters in a stream bed near the gem-rich area of Mogok, Myanmar. But, Dr. Kyaw Thu, a Burmese mineralogist-petrologist-gemologist with a Ph.D. from Yangon University, had a hunch this stone was unique when he acquired it at the Chaung-gyi market.

The International Mineralogical Association confirmed that the mineral was unlike any of the other 6,000 identified minerals in its database and officially recognized kyawthuite as a new mineral in 2015.

Named after Dr. Thu, kyawthuite (pronounced cha-too-ite) is extraordinarily dense (eight times the density of water and double the density of ruby). Its high density is attributed to bismuth, one of the three main elements that make up the chemical formula of the stone. The other two elements are antimony and oxygen, with a trace of tantalum.

Gemologists have wondered out loud why kyawthuite could exist in only one place on the planet. While bismuth and antimony are rare metals, they are not impossibly rare. Yet, if kyawthuite’s formula has manifested outside of Mogok, those crystals have yet to be unearthed.

Credit: Image courtesy of Natural History Museum of Los Angeles County.