Gas Stalagmite?? · AditNow Community

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keithwn
50.2% (Neutral)
Newbie Topic Starter

5 years ago

Found what looked like a stalagmite in Ratgoed Mine - but there was no water dropping down onto it. Instead it had gas bubbling up every few seconds (the 2 occasions in this video were very weak - most of the gas bubbles were stronger than this.)

Any ideas as to the origins of this formation and what might be called?

See

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John_Smith
50.2% (Neutral)
Newbie

5 years ago

You can't form such features from gas/ You have to have a fluid (water) which contains dissolved minerals which are picked up through the rock because rainwater is slightly acidic (carbonic acid from the carbon dioxide in the atmosphere). A gas can't hold minerals.

It is most likely that it could be an older formation that had water flow in the past that doesn't exist now.

50shadesofgreen
50.2% (Neutral)
Newbie

5 years ago

I thought stalagmites always occurred due to mineral laden fluid dropping from above. That means there always needs to be a corresponding stalactite above it?

Is it possible that the gas bubbles were not really drips falling into a pool? I would have covered it for a while to see if that stopped it.

Does gas come up from deep underground, other than volcanic? Natural methane perhaps? Which would suggest a detectable odour? - (Just been to Rotorua).

keithwn
50.2% (Neutral)
Newbie Topic Starter

5 years ago

Absolutely certain there was no water dropping down into it. There were gas bubbles (often much stronger than those captured in the video) which displaced mineral-laden water over the lip of the formation presumably causing it to build like a stal.

From the colour, it's been suggested that the mineral might by sulphur dioxide which I think is often associated with rock faulting and that these formations were essentially fumaroles (or solfatara). However, they only seem to be associated with volcanic activity which is of course not relevant here.

Nearby there were deposits of iron pyrites which is iron sulfide and associated with sulphur gas I believe.

There was at least 1 other smaller formation close by

dtyson
50.2% (Neutral)
Newbie

5 years ago

It's an interesting structure! The presence of Iron pyrites in the mine could produce sulphur dioxide, but hydrogen sulphide is much more common (and dangerous). It is possible the water contains dissolved calcium salts which could react with sulphur dioxide to produce gypsum (calcium sulphate) which is insoluble in water and so would accumulate and could build such a structure. The colour is probably due to traces of iron.

I have seem something similar in Garreg Boeth mine, the structure looked like a mini-volcano and was just under the water surface. The mine water was rich in calcium salts and I think dripping water & periodic dry spells when the water pool started to evaporate resulted in a sort of gour pool formation, but perfectly circular.

Dave

keithwn
50.2% (Neutral)
Newbie Topic Starter

5 years ago

Thanks - really interesting
Someone tells me they are known as 'shitatites' and are concentrations of earth salts and ochre etc

Ty Gwyn
50.2% (Neutral)
Newbie

5 years ago

Methane is odourless.

joso
50.2% (Neutral)
Newbie

5 years ago

I saw this two weeks ago, and I've seen an identical one (or several, rather) in Pantmawr. They seem just like the hours/rimstone formations you get in Pantmawr.

keithwn
50.2% (Neutral)
Newbie Topic Starter

5 years ago

Thanks
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