Two extremely rare minerals discovered deep within a Siberian mine have been found to share properties with lab-made materials called metal-organic frameworks (MOFs). Until now, it had been assumed that these synthetic structures were completely absent from nature, so the discovery of two organic MOFs has understandably left researchers somewhat stunned.
MOFs are made of polymers of hydrated metal ions, carefully designed in order to form voids and channels, typically only a few nanometers wide. These hollow spaces enable the storage of gasses such as hydrogen and carbon dioxide, making them potentially highly useful for removing harmful gasses from the air or even as fuel cells.
In a new study in the journal Science Advances, researchers reveal that two minerals named stepanovite and zhemchuzhnikovite – both of which were found in a mine near the Lena River in Siberia – actually mirror MOFs. Incredibly, and perhaps somewhat frustratingly, these two freaks of nature were discovered in 1942 and 1963 respectively, yet scientists did not realize just how unique and potentially useful these minerals were until much more recently.
Speaking to Gizmodo, study co-author Tomislav Friščić said that “one conclusion I can make is, if it were possible in the ‘40s to perform structural analysis like this, then the whole area of MOFs would have been accelerated by 50 years.”
After reading about stepanovite and zhemchuzhnikovite in a mineralogy journal, the researchers decided to synthesize them in the lab in order to investigate whether their structure matched that of MOFs. In doing so, they discovered that both exist as “thin veinlets, which consist of green transparent grained or fibrous aggregates,” arranged in such a way as to form openings and channels – just like those found in MOFs.
This finding was later confirmed when the study authors managed to track down actual samples of naturally-occurring stepanovite and zhemchuzhnikovite, confirming that they matched their lab-made copies.
Such structures had never previously been documented in non-synthetic minerals, leading the researchers to suggest that there may be yet more natural MOF-like minerals out there, if only we knew where to look.
Significantly, the authors believe that stepanovite and zhemchuzhnikovite were probably formed by the unique geological environment in which they were found, some 230 meters (755 feet) below the surface, in the permafrost zone. If any other natural MOFs do indeed exist, similar subterranean environments might therefore be good places to start looking for them.