Scientists from St Petersburg University have discovered an intriguing new mineral atop the Tolbachik volcanic complex, located in the Kamchatka Peninsula at the very far East of Russia. The mineral, called petrovite, has been reported in the journal Mineralogical Magazine.
The aqua mineral was first collected almost two decades ago, but a recent analysis revealed the composition of the mineral and how curiously the atoms within the mineral are organized. Petrovite is made of oxygen, calcium, sodium, sulfur, and copper (this is its chemical formula Na10CaCu2(SO4)8).
“The copper atom in the crystal structure of petrovite has an unusual and very rare coordination of seven oxygen atoms. Such coordination is characteristic of only a couple of compounds, as well as of saranchinaite, which was discovered by our colleagues from St Petersburg University – the research team of Professor Oleg Siidra,” project manager Professor Stanislav Filatov said in a statement.
The saranchinaite mineral has other important connections to petrovite beyond a similar structure. Saranchinaite was also discovered on Tolbachik, so the researchers hypothesize the petrovite could be a product of the reaction between saranchinaite, calcium sulfate, and sodium sulfate.
The proposed formation mechanism is only a hypothesis at present, the team stresses, but it’s one worth investigating. Understanding how such a mineral forms could have several materials science applications.
The mineral is structured in porous frameworks and sodium atoms are free to move among the voids. This ability could make the material ideal as a cathode in sodium-ion batteries. There are issues with the material itself, unfortunately, but understanding and tweaking how the mineral forms may be of use.
‘At present, the biggest problem for this use is the small amount of a transition metal – copper – in the crystal structure of the mineral. It might be solved by synthesising a compound with the same structure as petrovite in the laboratory,’ said Stanislav Filatov
The Tolbachik volcanic complex is a volcano that keeps on giving. Over 130 minerals, including alarsite and tolbachite, have been discovered here.
The area has two volcanos, Plosky (flat) Tolbachik and Ostry (sharp) Tolbachik, which are 3,085 and 3,682 meters (10,121 and 12,080 feet) respectively. The area witnessed a major eruption in 1975 and a smaller one from November 2012 to September 2013. The last led to the formation of several lava caves.