What is the rarest mineral on Earth?
Most human eyes have seen the mystical beauty of quartz, possibly without knowing that it is the most abundant mineral on Earth, but what is the rarest?
Minerals are scattered all over our planet, from glittering specks in gravel or sand to true hidden gems. According to the American Geological Association (opens in new tab)minerals are naturally occurring elements or compounds that are inorganic, meaning they contain none carbon. Each type of mineral shows order in its internal structure and has a unique chemical composition. The shape a mineral’s crystals take, as well as its other physical properties, can vary.
The rarest mineral on earth is kyawthuite. Only one crystal is known, found in the Mogok region of Myanmar. Caltech’s mineral database (opens in new tab) describes it as a small (1.61-carat) deep orange gemstone International Mineralogical Association (opens in new tab) officially recognized in 2015.
However, little is known about kyawthuite, so let’s move on to the second rarest mineral in existence. This is painite, which appears as deep red hexagonal crystals (although there are some pink exceptions). Although painite is now easier to find than it used to be, this mineral is still rare and its chemical structure makes it something of a scientific enigma.
In 1952, English gem collector and dealer Arthur Pain acquired two crimson crystals in Myanmar, according to George Rossman (opens in new tab)a professor of mineralogy at CalTech, who has been researching painite since the 1980s and an extensive database (opens in new tab) of all the samples he analyzed microscopically.
Pain thought the crystals were rubies, for which the region is famous, but unbeknownst to him, they were actually something much rarer.
Painite (which took Arthur’s surname) is sometimes excavated along with rubies and other gems. That explains why Pain assumed the crystals were rubies when he donated them to the British Museum in 1954 for further study, according to Rossman. Another sample of painite from Myanmar turned up in 1979, and until 2001 those three crystals were the only known specimens of painite in the world.
The very first painite crystal discovered, known as painite #1, was later analyzed by Rossman. His latest research on pain was published in Mineralogical Magazine (opens in new tab) in 2018.
“I conducted [studies] of the [first] example,” he told Live Science. “[My results] became the yardstick by which further discoveries of painite were confirmed.”
Through this research, Rossman has determined which elements painite consists of. Infrared spectroscopy uses infrared radiation to identify elements based on how they absorb, reflect and radiate that light. Raman spectroscopy uses a laser to scatter visible, infrared, or ultraviolet light, causing the molecules to emit unique vibrations that make them identifiable.
Rossman also found that there was an error in the chemical composition originally determined by scientists at the British Museum. Although they correctly identified aluminum, boron, calcium and oxygen, the element zirconium was missing. Another thing Rossman discovered was what gave painite its reddish hue; It contains trace amounts of vanadium and chromium that make it look deceptively like a ruby.
But what makes pain so rare? First, it is only found in Myanmar, but the real reason lies in its formation. Painite is a borate crystal, meaning it contains boron. It also contains zirconium. Boron has a notoriously difficult time bonding to zirconium. In fact, painite is the only mineral in which the two are found bound in nature. While the reason is still unclear, zirconium and boron have not been found together in significant concentrations, as Rossman said. It is also thought that these elements may not be very stable compared to other elements they might bond with.
“As far as I know, no one has done a serious study of what it takes to form pain,” Rossman said. “I don’t know of any attempt to synthesize it in a lab.”
What Rossman does have an idea about is why painite and so many other gems, such as kyawthuite, are found in Myanmar. When the ancient supercontinent of Gondwana began to split about 180 million years ago, India crept north and collided with what is now South Asia. Pressure and heat from the impact formed a treasure trove of rocks, many of them precious stones. He thinks the boron in painite and other borate minerals may have come from shallow seas around the newly formed landmass.
Rossman has many crystals suspected of containing pain sent to him for identification. Some have been hidden in plain sight for decades, as they were often stashed away in bags of rough gems or in the hands of dealers and collectors who misidentified them.
Painite suitable for luxury jewelry is hard to find and is valued at up to $60,000 per carat, Rossman said. What determines the price can be subjective, but the fewer flaws the better.
It should be noted that there are ethical concerns about mining in Myanmar, also famous for other gems and specimens of small prehistoric creatures trapped in amber. Human rights watch (opens in new tab) raises awareness about human rights violations by the military government, which benefits from the mining industry, which has unsafe and disease-ridden mines, forced labor and child labour. Some jewelers refuse to buy gemstones mined there and some scientists for this reason refuse to study samples (opens in new tab) from this country.
Painite is now more common than it once was. In 2005, multiple crystals began to appear, all within that year, and most of the painites are now found in the Wet Loo and Therein Taung regions of Myanmar.
Although painite no longer bears the crown of the rarest mineral, it is still a true gem.
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