Seeing Stuey's photo of Terras mine reminded me of another, namely South Terras 1878-1929 with the exception of the war years.
This mine was a producer of Radium and had the dubious practise of selling tailings sand to farmers as a radio active fertilizer!

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It does get a lot of attention, according to the lady in the Mill. The small building opposite the mill has chunks of pitchblende in it. People have been up the adit taking readings and I wonder how far you can get. Here's some material to digest.

http://www.dangerouslaboratories.org/rcw3.html 

and

http://www.wpb-radon.com/Radon_research_papers/2001%20Daytona%20Beach,%20FL/2001_07_Two%20Abandoned%20Metalliferous%20Mines%20in%20Devon%20and%20Cornwall,%20UK%20--%20Radon%20Hazards%20and%20Geology.pdf 

It could be an interesting trip, with the right PPE! ie BA.

I gave the impression that the mine reopened in 1918 in fact it was 1920. The mine from 1912 was owned by a company called The Societe Industrielle du Radium and the ore was sent to a place in france called Gif for the extraction of Radium and Uranium.
When the mine reopened in 1920 this work was transferred to South Terras. The mine was only worked during the summer months, pumping was suspended in the winter

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Another subject that has to be put in context,
Mme. Curie developed methods for the separation of radium from radioactive residues in sufficient quantities to allow for its characterization and the careful study of its properties, therapeutic properties in particular.

Mme. Curie throughout her life actively promoted the use of radium to alleviate suffering and during World War I, assisted by her daughter, Irene, she personally devoted herself to this remedial work.

Hindsight again with 20/20 vision.

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Talking of South Terras, this is how the works were described in 1923. I’ve included a picture of the booklet from which it came.

On the subject of Radium, the total amount of Radium extracted was merely a few grams!

I had to photograph the pages rather than put them on the scanner and risk burgering the spine.


🔗Personal-Album-342-Image-34428[linkphoto]Personal-Album-342-Image-34428[/linkphoto][/link]


🔗Personal-Album-342-Image-34426[linkphoto]Personal-Album-342-Image-34426[/linkphoto][/link]

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Not a bad article.
http://www.dangerouslaboratories.org/rcw3.html 

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Stuey, Roy, Spitfire, liked the link... visited briefly way back and couldnt really get much gen back then on it. Fascinating history. Excuse my ignorance here but also what would the ore have looked like physically in the vein? How would they have known it was so radioactive worth mining?

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The lode was discovered in a quarry as a green vein and given the local name Green Jim. on opening up the vein investigations shewed that it contained Uranium, containing Torbernite, Zippaeite and Pitchblende. This was in 1878 and mining operations started in 1887

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Stuey, Roy, Spitfire, liked the link... visited briefly way back and couldnt really get much gen back then on it. Fascinating history. Excuse my ignorance here but also what would the ore have looked like physically in the vein? How would they have known it was so radioactive worth mining?

I remember doing this as a science project at school, but to make sure of my facts I've just checked them on the net. The grey matter still seems to be good in this area!

Antoine becquerel was chasing up a branch of Roentgen's work ( Discoverer of X-Rays) and was particularly interested in Fluorescence and Phosphorescence in certain minerals.
Purely by accident he placed an unexposed photographic plate in a drawer that also contained some crystals of Uranium (probably Torbernite) which exposed the plate leaving localised 'fogging' on the emulsion. Although he noted this, Becquerel continued with his work and it was others that picked up on the strange phenomenon and investigated it further.
Enter the Curies........
This curiosity helped bolster their work and it was they that in 1898, were responsible for first coining the term Radioactivity, from the property of this material to turn air into a conductor of electricity.

The main Minerals are;

Pitchblende , Proto peroxide of Uranium - Commonly found as a brownish blackish, amorphous ore weighing about the same, volume for volume, as Cassiterite (tin ore). Typical analysis yields about 84% Uranium.

Torbernite (The 'Green Jim' of South Terras) Hydrated Phosphate of Uranium and Copper - Commonly in green tabular crystals, approximately half the weight of Pitchblende, and some specimens were so highly phosphorescent when found, they would glow in the dark.
Typical analysis yields about 60% Uranium, with Copper around 9%

There are a few lesser minerals that also contain Uranium.
Autunite - A yellow scaley mineral, in old books sometimes refered to as Uranium Mica. Typical analysis 62% Uranium Oxide.

Zippaeite (Uranium Oxide) - An earthy powdery lemon yellow Ochre. Typical analysis similar to Autunite.

There are several others but the above seem to form the bulk of production of the worlds supply of Uranium.

It's worth noting that Uranium metal itself is not as radioactive as Pitchblende, which by comparison is absolutely 'leaping' 😮 It was this fact alone that lead the Curies to isolating the other elements such as Polonium and eventualy Radium.

We've still got loads down here in Cornwall. Wheal Edward and Wheal Owles are 'Hot' as are most of the Carbis Bay Mines, along with sections of the beach!!!!
You can get tanned both sides at the same time if you know where to go. 😮 :lol: :lol:

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Thanks for that in depth response.... most alarming re the beach tho!!! Tho it has mademe re-consider taking the mother n law... she could have her own special bit of beach :devil:

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Here's a little more on the 'Green Jim' Subject.
I had a rumage about and came up with this. Collected from an ore chute in 1986. We didn't stay in there long as the Geiger counter we were using to monitor background (lol) couldn't handle the peak levels and the analogue meter just kept giving us FSD ( Full Scale Deflection).
peak levels off the clock. 😮

Anyway, here is the sample, and a microscope shot of the crystals themselves.

Sample dimensions 75mm x 30mm

🔗Personal-Album-342-Image-34711[linkphoto]Personal-Album-342-Image-34711[/linkphoto][/link]

Typical tabular shaped crystals of Torbernite.
Largest crystal here is 1mm across Mag = 20X approx

🔗Personal-Album-342-Image-34712[linkphoto]Personal-Album-342-Image-34712[/linkphoto][/link]

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Tremendous Pics Roy, thanks, least I know what it looks like now!!

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I remember visiting someone in the Kerrier area with a large lump of local pitchblend on the hearth, as an ornament!
Wonder if it's still there?

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wonder if they are still there ???? hot stuff that !

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This is fascinating stuff.

There is a bit of a mystery concerning what is in Dines and what was on the map outlined here:-

http://www.dangerouslaboratories.org/rcw3.html 

Dines seems to suggest that (from memory) that the grilled adit was a later addition to the mine and the U lode was in fact stringers where radioactive water entered the workings (Under Tolgarrick Mine rather than S Terras).

It's one of those places that has long held my curiosity and I wish to have a proper look at some point. However, at 18mSv per hour, we are talking some pretty serious exposure. I had a chat with a certain nuclear safety officer and he reckoned that 18mSv was probably a better idea to avoid. He agreed with me in that alpha radiation is pretty easy to protect against and suggested the use of diving bottles.

I would be actively keen on having a proper look (with the relevant permissions, etc) as I imply from the other report that the "inner workings" were more akin to caving than a walk-in.

[tweak]Link made clickable - srl[/tweak]

I once saw a report written in the mid 1980's giving radiation figures (underground) for both South Terras and Tolgarrick.
The figures for Sth. Terras were very high indeed. The levels in Tolgarrick were extraterrestrial, with readings measured in Mega Beck's !!!! 16M from memory... :ohmygod: 😮 😮 .
Give me cosmic rays any day :blink:
I have a copy of it here somewhere but have'nt seen it in a long while. Time to go root it out I think.

Have just read one of your links and was reminded of the authors name - Dr Gillian Pearce. She also ent me a short video filmed inside Sth Terras including her dog being floated in on a surf board. Very interesting.

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Does that mean you could get a suntan underground? 😉

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Roy, It's this one:-

http://www.wpb-radon.com/Radon_research_papers/2001%20Daytona%20Beach,%20FL/2001_07_Two%20Abandoned%20Metalliferous%20Mines%20in%20Devon%20and%20Cornwall,%20UK%20--%20Radon%20Hazards%20and%20Geology.pdf 


I'm pretty sure......

What you have to remember is the correlation between Bq and Sv..... and Grays and all those other units! I think the one of primary concern is the absorption which in the case of alpha is limited largely to your eyes and breathing tract. Isolating these is relatively easy.

I've heard of Terras being measured in Gas Marks as well as suncream factor required.....

It all got originally interesting when I was looking into digging the back of Old Gunnislake adit (bonney lode) where I think you had 8 hours in a year in order to obtain your 20mSv (mine workers yearly maximum dose). I had a proper problem finding a BqSv correlation and it is pretty bloody full on. How they came upon 18mSv/hr escapes my memory but I think it may have been one of those badgey things. Again, relating actual dose to the radiation present involves all sorts of other factors....humidity, air-particle loading, isotopes present, how the place is ventilated influencing the equilibrium of species.... it's pretty full on.

I think the best course of action is to get some BA on and get in there.

Roy, am I right in thinking that there is more than one way into the mine? I assume tin lode was worked.

As I previously mentioned, the site up on the hill has been largely obliterated. I couldn't find anything of significance there apart from the side of a big tip.

Totally off topic of radioactivity and Uranium, I gathered from the lady in the mill that someone had been making noises about the tin left in there. According to her there was at one time interest as it was meant to be considerable.

I can't see it myself.

I read that report on your link and that wasn't the one I saw back in the 80's.
The Bq, Sv, Curies, Rems, thing really spun my head when I researched it some years ago for an article I wrote. I still have to re cap when faced with some of these oft mis-quoted units, especially the Becquerel or 'Buggerall' as a member of staff at the NRPB described it to me.
My teeth aren't glowing in the dark yet and as far as I know, I cant expose photographic plates by sitting on them, so I guess things aint too bad.
On the subject of tin at Sth. Terras, I've never seen it but did hear the same tale as you, and guessed that the Uranium, fetching a better price and simpler to process, was sought out over the tin to make the much sought after 'Quick Buck'.
According to Dines' description of the geology, it appears to be something of a mixture of upper zone minerals, Fe,Zn,Ag accompanying Cu,Sn,As along with Cu-As combinations with the U as a later component, the concentrations of which seemed to be patchy at times with values from 1 to 6 milligrams per ton but averaging 1mg /ton over the lengthof the lode.
with so many minerals present, It reads like it should have been open cast mined, but I guess the deposit was too deep at 50fms, and the concentrations of those minerals too low.
As for entrances. I can only say that I visited the site once and didn't much care for sticking around too long to explore any other possible routes into the mine. I had a pick over the tips and found some hot spots in the nearby fields where the sheep were grazing (30 & 40x background), with a few odd kicks up to the end stop.
Dealing with Alpha isn't much of a problem and a good paper mask will stop particles being inhaled on moist air.
Wrap yourself in tin foil for Beta, and break out the NBC suit and lead lined oversuit for the Gamma. :lol:
I'd like to see an analysis of the water in the adit, and one for the sheep too. 😮
Talk about a hot dinner......!!!!!

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I'm planning to have a good poke around with a half decent geiger counter.

The issue of livestock is an interesting one. I assume that being largely and alpha problem, it's a case of eyes/lungs for the sheep also. I wonder how many of the sheep have been contracting lung cancer!

I'm not convinced about the paper mask. Obviously charged particles are a bit more obvious than those without, but the pores in the paper are pretty bloody large compared to the atomic radii concerned! I suppose it's only the dust particles you are really worried about. From memory, the sort we are dealing with which are a threat to lungs are microscopic.

I'd have a wander up the obvious bit, but would like to have a proper go at the place at some point.

Alpha counters are either rare or expensive. The one I have access to has flashing lights and is about as big as a suitcase. Looks like something from Dr Who.

Edit:- for the bit about sheep, assuming they can drink standing water from around the mine, that would pose pretty big problems. I assume that the U/daughters are largely suspended in solution, rather than being truly dissolved. Semi irrelevant really as the sheep either gets nuked in it's soft tissues or cooked from the inside!

Either way, I don't imagine the farmer gives a toss and it's not like you smell mutton when you walk past! Probably largely a theoretical gripe.