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Is this an ancient natural pyre, where underground fires have raged for thousands of years?

By 0 and 0 and 0
06 January 2016


'There was something burning underground. It was minus 35C but my legs became warm immediately.' Picture: Roman Filenko

On the face of it, this is not a volcano in the TransBaikal region of southern Siberia, but it has many similarities. The ground is hot to the touch, and people who fall are at risk of severe burns. 

The obvious explanation is that a disused Soviet mine - the Chernovskoye brown coal deposit - is on fire beneath the surface, and while true, this may be only part of a story that is intriguing scientists, and which could hold worrying consequences.

A local scientist became intrigued by the phenomenon after driving past the site six years ago and seeing smoke billowing from beneath the surface. The Siberian Times contacted Roman Filenko, a junior researcher at the Institute of Natural Resources, Ecology and Cryology in Chita, to ask him about his conclusions.

Here he explains his fascinating scientific detective work, which led him to one of only a handful of discoveries in the world of exceptionally rare mineral Rosenbergite, but also to a theory on what has is causing this strange spectacle. 

'My acquaintance with these fires started in January 2010,' he said. 'All scientists 'suffer' from curiosity and I am no exception so when I drove past this area in winter and saw some smoke, I asked the driver to stop by to see what it was.

Coal burning underground

Coal burning underground

Coal burning underground

The soil is hot to the touch, and people falling are at risk of burns. Pictures: Ksenia Zimina, Grigory Kuksin

'My first thought was that it was a burning dump. Yet there was no rubbish but I could see a lot of steam coming from the ground. There was something burning underground. It was minus 35C but my legs became warm immediately. 

'The steam came from each and every little crack. It all looked quite like fumaroles (openings in the planet's crust, often in the neighbourhood of volcanoes, which emits steam and gases). 

'My driver told me that he had seen this smoke for three years. Locals are aware of this fire, and got used to it and explain that 'they used to mine coal here, the abandoned coal oxidizes and burns'.

'It was quite a scientific explanation. I was curious and started observing it, analysing what was forming in those hot streams, and which minerals were present. One of the specialisations of our laboratory is modern mineral formation, that is minerals forming in front of our eyes. The first thing I was interested in was mineral associations: which chemical elements make up the rocks here. 

Underground burning

Roman Filenko

Roman Filenko: ''All scientists 'suffer' from curiosity and I am no exception.' Pictures: Roman Filenko

'Samples were collected in 2010, prepared and sent to the Institute of the Earth's Crust in Irkutsk. The samples got lost there. The results were ready only in 2012 and attracted more interest because they showed there were mineral associations typical for volcanoes.'

Yet this was not an area where volcanoes were known, and the rock structure is wrong for them to form. 

'Sulphur and ammonium sulphate were formed in the crater of the fumaroles, compounds of sulphur, oxygen, hydrogen and nitrogen. It was some sort of natural chemical laboratory. I found out that there were two modifications of sulphur in the samples, alpha-sulphur and beta-sulphur, the structure of their molecules is different. It can be seen on thermograms during thermal analysis. 

'In 2013 we found a very rare mineral in one sample. I received a letter with three exclamation marks from the Institute of the Earth's Crust. It was a particular aluminium fluoride, AlF3 + 3H2O. It's a compound of aluminium, fluorine and three molecules of water. The mineral is also known as Rosenbergite.

'This is a mineral also typical for volcanoes. It was also found at Mount Erebus on Ross island in the Antarctic, and in Tuscany, in Italy. Later, I studied the publications of my foreign peers and discovered that there are similar finds in volcanoes in Iceland. There is also unconfirmed data about Rosenbergite at burning dumps in Germany.

Underground burning

Underground burning

New minerals forming

New minerals forming

'It was some sort of natural chemical laboratory.' Pictures: Roman Filenko

'After comparing our data with that in foreign publications we became sure that the mineral found here was Rosenbergite. This led to an immediate question - perhaps, we do have a volcano here? But if there was a volcano, it would mean different tectonics and geological conditions. Here we have a typical Jurassic Cretaceous sediments. There can be no volcano here.

'There is an interesting geological object called Krasnaya Gorka (or 'Red Rock') close to these underground fires. There were unique palaeontological finds made here, imprints of plants and insects. 

'A lot of researchers thought that there was, indeed, a volcano at this place some time ago. Clay had warmed up and become naturally baked. At first I thought the same, but later I discovered that the coal was burning at a huge temperature and so massively. And everything became clear: Krasnaya Gorka was also a result of fires, but not modern ones. Ancient fires.

'Different sources say that coal tends to heat up and self-ignite. It's an interesting process which hasn't been fully explained by science. There are several theories explaining why coal flares up. Some believe that fire is provoked by micro organisms. Others say that impurities play bigger role.



'It's a compound of aluminium, fluorine and three molecules of water. The mineral is also known as Rosenbergite.' Pictures: Roman Filenko

'There is always iron sulphide which oxidizes and produces sulphuric acid, and the acid acts as a catalyst speeding up the oxidizing process by 2 or 3 times. Heat builds up, the temperature gradually rises, at first coal starts smoldering and once the temperature rises over 200C it starts burning. 

'I took school children there on an excursion. At first we went to a recent dump, and when we returned there 6 months later, we discovered that it was already burning. We found not only sulphur and sulphates there but such formations as asphalt-like crust. This crust is black and looks like asphalt, quite smelly because of aromatic hydrocarbons, and I believe organic minerals will be found there.

'The dynamics are not quite optimistic. There are old, long-living fires and new ones. Something needs to be done about it. The fire is becoming more and more intense. Earlier, this abandoned mine was burning in one place only, now almost the entire mine is aflame. 

'The coal mine is close to a residential district, and an airport is here too. There is a railway nearby, carrying hazardous freights such as sulphuric acid and uranium. Of course, these are in special containers. It is safe but still the railway is under threat. If the mine is left abandoned, if it is not reclaimed, we will be in a lot more trouble. As of today, the territory of the fire is half a hectare, some 5,000 square metres. It's not too big, but it's not small. If it's not brought under control, the area will increase. 




'I found out that there were two modifications of sulphur in the samples, alpha-sulphur and beta-sulphur, the structure of their molecules is different.' Pictures: Roman Filenko

'The underground fire is constantly moving. Since 2010 it has moved by 5 metres, at the same time the front of the fire moves by 1-2 metres a year. It's expanding in all directions, so the area is increasing. Besides, locals keep digging the old mines illegally. 

'It is necessary to carry out regular thermal monitoring. Where a fire has already started, it is necessary to limit the burning area, localise it. The task of researchers is to suggest the best method to use in a particular case.

'It's not only a local problem. Coal is burning in Tuva and Kuzbass in Siberia and also Bulgaria. If it's an old, long-living fire, you can fall into the ash. I fell into the ash quite deep, up to my waist. And these rocks are cooling slowly, you can get burned. It's good, we haven't had any victims. There is a road nearby, which slumps. It was fixed recently but the road keeps slumping.

'This is a very interesting place in terms of mineralogy, for fundamental science. It can be turned into a sightseeing object for scientific mineralogical tourism. However, I managed to find Rosenbergite only once. I couldn't find it in other samples. Perhaps, it was at a certain stage of burning. It was in layers with lots of fluorine and aluminium. It was a once-in-a-lifetime phenomenon. I can't see it happening now.



Mascagnite, a rare ammonium sulfate mineral, which occurs in fumaroles and associated with coal seam fires. Pictures: Roman Filenko

'It is clear to me that there were fires in this particular place dozens of thousands of years ago. The upper layers have burnt out, the lower ones are still there. In modern times, there were fires here back in the 1950s. 

'There is a report by geologists from St Petersburg dated 1963 where they describe baked rocks left after modern fires. They reported that there was no snow even in winter, but instead green grass. I couldn't see the grass, but there is green, beautiful moss.'

The Institute of Natural Resources, Ecology and Cryology in Chita is part of the Siberian Branch of the Russian Academy of Sciences.

Rosenbergite is a colourless mineral with crystals which are tetragonal to dipyramidal, named after Philip E. Rosenberg, an American geochemist. It is found in the Celtine Mine in Tuscany, Italy and Mount Erebus, Ross Island, Antarctica. It is not radioactive. 

Read our previous story: 

Raging underground fires in minus 23C near Chita

Comments (4)

Unfortunately these toxic emissions that emanate from worldwide underground coal-seam fires are making a huge contribution to the increasing, sudden and abrupt climate change, as a direct result of Anthropogenic Global Warming, and yet this noxious source of pollution could be greatly mitigated by simply injecting flame-retardant foam downhole to completely smother any underground coal-seam fires of oxygen; via modern oilfield drilling and completion technology.
Chuck Heppner, Dolores, Colorado - United States of America
19/01/2016 23:42
I grew up in a coal mining town in Australia where the coal used to regularly catch fire. At the time, they said it was "sub-bituminous grade 4 black coal", and that exposing it to water & air would make it spontaneously combust. We all knew not to leave bags of coal leaning against anything flammable, because we risked other things catching alight too. The slag heaps were also burning in underneath, & had been for years.
Judi, Australia
13/01/2016 07:33
Not easy to translate for me, but very interesting article. Is fire the same that in ancient coal mine in Saint-Etienne town in Massif Central mountain in France?
This ancient mine was stop to exploit for ~100 years.But there are alway fire at "petit clos" .Thanks you for this article, with beautiful pictures
Jocelyne, FRANCE
09/01/2016 21:42
Good scientists can even make a hot puddle seem fascinating. Excellent pictures, too.
Bernard, Los Angeles
09/01/2016 05:21

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