Remnants of lava flows from a volcano can serve as treasure troves of numerous minerals. While more than often the mineral deposits are of familiar compositions, new and unique minerals reveal themselves occasionally. Scientists from Russia have reported the discovery of one such mineral from the deposits of lava flows formed by the famous Tolbachik Volcano in far-eastern Russia.

According to scientists from St. Petersburg University, the mineral known as petrovite shows excellent iconic conductivity (i.e) it can facilitate the movement of ions from one site to another, thereby, facilitating the conduction of current.

"The mineral is named in honor of Prof Tomas Georgievich Petrov (b. 1931) for his contributions to mineralogy and crystallography and, in particular, for the development of technology for the industrial fabrication of jewelry malachite," wrote the authors about its name.

Looking for Minerals In Volcanic Deposits

Petrovit
Petrovite SPbU

Co-author Prof. Stanislav Filatov and his colleagues have been analyzing the mineralogy of scoria cones (steep conical wall formed around a volcanic vent) and lava flows of fumaroles (openings in the earth's surface that release volcanic gases and steam) in the Kamchatka peninsula in far-eastern Russia. These formations came into existence during the eruptions of the Tolbachik Volcano in 1975-1976 and 2012-2013.

What makes this territory unique is its mineralogical diversity. Over the course of years, scientists have unearthed several dozens of new minerals in this region. Interestingly, most of these minerals are rare and one-of-their-kind in the world.

A New Unique Mineral

In the current study, the authors learnt that petrovite, whose chemical formula is Na10CaCu2(SO4)8, is found as blue globular aggregates of tabular crystals with gases trapped in them (also known as inclusions). They reach a maximal dimension of 0.2 mm.

Petrovite
Petrovite SPbU

"'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," explained Prof. Filatov.

Properties That Can Be Utilized

The mineral is comprised of copper, oxygen atoms and sodium-sulfur, which lead to the formation of a porous structure. Voids that are found within the framework are connected to each other through channels within which relatively small sodium atoms can traverse. Therefore, this has led researchers to confirm that the structural configuration of petrovite presents a potential for ionic conductivity, which can be leveraged as material for the cathode in sodium-ion batteries.

"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 synthesizing a compound with the same structure as petrovite in the laboratory," expressed Prof. Filatov.