What is the rarest mineral on Earth?
Most human eyes have seen the mystical beauty of quartz, possibly unaware that it is the most common mineral on Earth, but which is the rarest?
Minerals are scattered all over our planet, from bright spots in gravel or sand to real hidden gems. According to the Geological Society of the United States (opens in a new tab)minerals are natural elements or compounds that are inorganic, that is, they do not contain carbon. Each type of mineral has order in its internal structure and has a unique chemical composition. The shape that 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 to exist, found in the Mogok region of Myanmar. Caltech Minerals Database (opens in a new tab) describes it as a small deep orange gemstone (1.61 carats) that the International Mineralogical Association (opens in a 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 more easily found than before, this mineral is still rare and its chemical structure makes it a scientific enigma.
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In 1952, English gem collector and dealer Arthur Pain acquired two crimson crystals in Myanmar, according to George Rossman (opens in a new tab)professor of mineralogy at CalTech, who has been researching painite since the 1980s and maintains an extensive database (opens in a new tab) of all the samples he has analyzed microscopically.
Pain thought the crystals were rubies, which the region is famous for, but unbeknownst to him, they were actually something much rarer.
Painite (which took Arthur’s surname) is sometimes discovered along with rubies and other gemstones. This explains why Pain assumed the crystals were rubies when, according to Rossman, he gave them to the British Museum in 1954 for further study. Another sample of painite from Myanmar appeared in 1979, and until 2001 these three crystals were the only known specimens of painite in the world.
The first painite crystal discovered, known as painite #1, was later analyzed by Rossman. His latest painite study was published in Mineralogical Magazine (opens in a new tab) in 2018.
“I drove [studies] from [first] sample,” he told Live Science.[My results] became the standards by which new discoveries of painite were confirmed.”
It was through this research that Rossman determined what elements make up painite. With infrared spectroscopy, infrared radiation is used to identify elements based on how they absorb, reflect, and emit this light. With Raman spectroscopy, a laser is used to scatter visible, infrared, or ultraviolet light, causing molecules to emit unique vibrations that make them identifiable.
Rossman also found that there was an error in the chemical composition originally determined by British Museum scientists. Although they had correctly identified aluminium, boron, calcium and oxygen, the element zirconium was missing. Another thing Rossman discovered was what gave painite its reddish hue; It has traces of vanadium and chromium which can make it look deceptively like a ruby.
But what makes painite so rare? For one, it is only found in Myanmar, but the real reason lies in its training. Painite is a borate crystal, meaning it contains boron. It also contains zirconium. Boron has a difficult connection with zirconium. In fact, painite is the only mineral in which the two have been found together in nature. Although the reason is still unclear, zirconium and boron have not been found together in significant concentrations, Rossman said. It is also believed that these elements may not be very stable compared to other elements with which they could bond.
“To my knowledge, no one has done a serious study of what it takes to form painite,” Rossman said. “I’m not aware of any attempts to synthesize it in a laboratory.”
Related: How can we tell the difference between geological ages?
Why Myanmar?
What Rossman does have an idea is why painite and so many other gems, such as kyawthuite, are found in Myanmar. When the former supercontinent of Gondwana began to split about 180 million years ago, India drifted north and collided with what is now South Asia. The pressure and heat of the collision formed a treasure trove of rocks, many of them precious stones. He believes that the boron in painite and other borate minerals possibly came from shallow seas around the newly formed land mass.
Rossman has sent him many crystals suspected of being painite for identification. Some have been hidden from view for decades, often hidden in rough gemstone bags or in the hands of dealers and collectors who misidentified them.
Painite suitable for fine jewelry is hard to come by and is valued at up to $60,000 a carat, Rossman said. What determines the price can be subjective, but the fewer defects the better.
It should be noted that there are ethical concerns about mining in Myanmar, which is also famous for other gemstones and specimens of tiny prehistoric creatures trapped in amber. Human Rights Watch (opens in a new tab) raise awareness of human rights abuses by the military government, which profits from the mining industry, which has unsafe mines infested with disease, forced labor and child labor. Some jewelry companies refuse to buy gems mined there for this reason and some scientists decline to study specimens (opens in a new tab) of this country
Painita is now more common than before. Multiple crystals began to appear in 2005, all within that year, and most painites can now be found in the Wet Loo and Therein Taung regions of Myanmar.
Although painite no longer holds the crown of the rarest mineral, it is still a true gem.
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