by Most human eyes have seen the mystical beauty of quartz, probably not knowing that it is the most common mineral on Earth, but which is the rarest?
Minerals are scattered all over our planet, from glistening specks in gravel or sand to real hidden gems. According to Geological Society of America (opens in new tab)minerals are natural elements or compounds that are inorganic, that is, they do not contain carbon. Each type of mineral exhibits order in its internal structure and has a unique chemical makeup. The form 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, found in the Mogok region of Myanmar, is known to exist. Caltech Minerals Database (opens in new tab) describes it as a small (1.61 carat) deep orange gemstone that the 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 occurs as deep red hexagonal crystals (although there are a few pink exceptions). Although painite is now more easily found than it used to be, this mineral is still rare and its chemical structure makes it something of a scientific enigma.
Related: How long does it take to make petrified wood?
In 1952, English gem collector and dealer Arthur Pain acquired two crimson crystals in Myanmar, according to George Rossman (opens in new tab)professor of mineralogy at CalTech, who has been researching paintite since the 1980s and maintains an extensive database (opens in new tab) of all the samples he has analyzed microscopically.
Payne thought the crystals were rubies, for which the area is famous, but unbeknownst to him they were actually something much rarer.
Painitis (named after Arthur) is sometimes discovered along with rubies and other precious stones. This explains why Pain assumed the crystals were rubies when, according to Rossman, he donated them to the British Museum in 1954 for further study. Another sample of paintite from Myanmar appeared in 1979, and until 2001, these three crystals were the only known samples of paintite in the world.
The first paintite crystal discovered, known as paintite #1, was later analyzed by Rossman. His latest Painite study was published in Mineralogical Journal (opens in new tab) in 2018.
“I directed [studies] from [first] sample,” he told Live Science.[My results] became the standards by which further discoveries of paintite were confirmed.’
Through this research Rossman determined what elements make up paintite. With infrared spectroscopy, infrared radiation is used to identify objects based on how they absorb, reflect, and emit this light. With Raman spectroscopy, a laser is used to scatter visible, infrared, or ultraviolet light, which causes 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. While they had correctly identified aluminium, boron, calcium and oxygen, the element zirconium was missing. Another thing Rossman discovered was what gave paintite its reddish hue. It has traces of vanadium and chromium which can make it look deceptively ruby.
But what makes paintite 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 an extremely difficult bonding period with zirconium. In fact, painite is the only mineral in which the two have been found associated in nature. While the reason is still unclear, zirconium and boron have not been found together in significant concentrations, Rossman said. It is also thought that these elements may not be very stable together compared to other elements with which they could be connected.
“As far as I know, no one has done a serious study of what it takes to form paintite,” Rossman said. “I know of no attempt to synthesize it in a laboratory.”
Related: How do we tell the difference between geological ages?
Why Myanmar?
What Rossman has an idea about is why paintite and so many other gems, like kyawthuite, are found in Myanmar. When its ancient supercontinent Gondwana began to break apart about 180 million years ago, India drifted north and collided with what is now South Asia. The pressure and heat from the collision formed a hoard of rocks, many of which were precious stones. He believes that the boron in painite and other boric minerals probably came from shallow seas around the newly formed land mass.
Rossman was sent several crystals suspected to be paintite for identification. Some were hidden in plain sight for decades, often hidden in bags of rough gems or in the hands of dealers and collectors who misidentified them.
Painite suitable for fine jewelry is hard to find and fetches as much as $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, also famous for other gems and specimens of tiny prehistoric creatures trapped in amber. Human Rights Watch (opens in new tab) raises awareness of human rights abuses by the military government, which profits from the mining industry, which has unsafe and disease-infested mines, forced labor and child labor. Some jewelry companies refuse to buy gems mined there for this reason, and some scientists they refuse to study samples (opens in new tab) from this country.
Painite is now more common than it once was. Multiple crystals began appearing in 2005, all within that year, and most of the paintings can now be found in the Wet Loo and Therein Taung regions of Myanmar.
Although paintite no longer wears the crown of the rarest mineral, it is still a real gem.
