• BCRA NEWSLETTER MAY 2024

    Lots of info from BCRA

    The next online seminar is on Monday 10th June, 19.30 to 21.00 via Zoom

    Click here for more

The Mine Shafts Project. Hydrology.

The Old Ruminator

Well-known member
You may note a hint of irritation in my latest group ( team ? ) email. I may well have a finger prod on the old pc and knock up a piece about team digging. Ins and outs as it were.

Met Mike at 4.30 . We had loads of kit to carry so the plan was simplified. To be honest I was a bit piqued that Peter was going to Cothelstone on Monday with Martin rather than support efforts at the shaft .I did suggest he go up yesterday to do the holes in the other bit but he could not. 4.30 too late. Yes I know I did not get home until nearly 10pm. Anyway just two holes at that site is never enough as you need three in the floor and one in the boulder.
Mike started drilling here is his report.

"1x900mm, 5 x 600mm, 1 x 500mm and 2 x 400mm. Thermal cut out on the drill operated about 700mm into the 900mm hole. The drill was red hot and smoking big time. A couple of minutes later, it was working again, but still almost too hot to hold "

In the meantime I measured the water at 700mm. Then on my way to the other site I took a photo of the big drilled dead . The same diameter hole as the ones in the shaft.Thus denoting the origin of said boulder and showing that that part of the level is older. Going on I saw a pile of rocks below Brian's aven dig ( where he found God ). There had been a collapse from up there since last week. One rock remain jammed across the aven high up. I Cleared some of the debris down the shaft.Onwards over the bridge to " The Other Place ". The new probe went just over the top of the boulder for a metre finding no space anywhere.A bit of lode passes through on the left. The boulder is bigger than I thought.
Back to Mike struggling with the drill. We had probed forward 3.4m adding another metre to the probe done last week. Just got out in time to see the sun sinking in the west. All accomplished.

Review..

" The Other Place " would need a serious one off visit. A trip in itself if its worth progressing. Certainly not together with another effort in THITW. As THITW is the priority and will need a lot more work I cant see much happening at TOP unless Peter deals with it seperately. Personally I dont hold out much hope up there. THITW is progressing well. We make about 700mm per double trip. The airspace leads on and widens down to the right. I was annoying Mike by levering more bits out of the roof whilst behind him. At least the end bit is dry now.

Addition.

Brian was digging up in the aven when a large boulder fell on his head. It knocked his light out so all went dark. He thought " Is this death because it did not hurt ? " Me shouting up broke the spell. Perhaps we will call the aven " Brian In Heaven ".

Last nights video.

 

The Old Ruminator

Well-known member
Another load of gear dragged in.



The drill is getting warm.



Drill section on Triassic dead.



Waiting to drop at " Brian In Heaven " aven.



Got the sod there at last.



" The Other Place "

Lode marked. Big boulder X-X. Lump in floor Y. Note the probe rod. Man digging the road up said I could have some bits. 11.5mm dia plastic rigid pole used for pipework. Got a 3.5m length and two smaller bits.

 

The Old Ruminator

Well-known member
Do we have a match with what the miners drew c 1820 with what we see today ( left ) ? The stoping I have added in orange and if correct its buried by deads. Its been a long running discussion which way around the section runs. The two main published sources disagree.

 

The Old Ruminator

Well-known member
Pick marks in the coffin level. Trimming rather than digging.



Small overhand stope probably work by the tributors who where pickmen paid for the ore they obtained. In this case " lode " with sulphides of copper not as a mineral.



Triassic sandstone deads from the shaft in the 20m level. Placed there as the shaft progressed deeper.

 

The Old Ruminator

Well-known member
Flooded base of the shaft with my ladder on the SRT line. The water can be 7m lower than this getting very close to the adit at 30m.



Over stepped roof on the lode at the 20m level as left as the shaft progressed downwards. The shaft intercepting the 20m level near its termination.



My lunch at the 20m platform.



The others above on The Hole In The Wall platform at 15m. Daylight from the entrance tube through the cap.

 

The Old Ruminator

Well-known member
The Hole In The Wall.

Still following the lode and has encountered a mud choke seperating the lode by hypogenic solution. Some of the copper from here came in the form of grey slime as it seperated from the lode or was brought from depth by the rising fluids ( we will get to the technical bit later ).



Inside the choked vugh. Hypogenic cavity left. Seperated lode centre. Mud filled vugh right. Roof with hypogenic solution etching.

 

The Old Ruminator

Well-known member
Snigger you not Mr "I would rather be at Cothelstone ". The group did not like the text report as is so I shall report myself and ask the kind mods to delete that bit.
 

The Old Ruminator

Well-known member
Now where was I before the interuption ?

Oh yes about the copper. I knew nothing about mineral mining before this project so its been an interesting learning curve. Here we are looking for natural parts of a mine so the two sciences coincide. Hypogenic cave development and Hydrothermal mineral deposition. Both relatively new concepts to me and if anyone here knows better please step in.

On the last trip I asked myself " so where is the copper ? " As we are following Hypogenic cave development I looked for the Hydrothermal copper in the untapped " lode " that we are following. The miners referred to the Limestone and the Barite both as the " lode " or " leader " neither in the true sense of the term " lode " are true. It did make there contemporary reports sound good though and in many ways early mining was a game of bluff verses reality.

From the samples I brought home I deduced the following ( for the purist sorry I omitted the scale ).

The copper in the shallower softer parts of the " red " rocks ie the Triassic Sandstone came as carbonates.
The copper in the limestone came as Sulphides in our case Chalcocite ( " Cu2S, Copper Glance ") also from the softer rocks and clays as slime. (" Gangue Slimes " ). The Chalcocite was treated by the usual way with stamps and could produce %80 copper by weight from the Barite known to our miners as " The Heavy Spar ". Both being a secondary mineral in forms that displaced other minerals though the slimes came from the Hypogenic Vughs. These came as descrete pipes or bedding planes where Hypogenic activity was most active. ( The Hole In The Wall ).

The slime was " jigged " by running water through it in a hutch . Sieving if you like. Such work was undertaken by the women and boys.

Adjacent to the Limestone and Barite is the " Killas " essentially non productive but much easier to dig by hand though unlikely to support a Hypogenic void long term. The Killas is the limestone slates.

Sample.

Crystalline Chalcocite and Barite from the Heavy Spar in The Hole In The Wall.









Comments or amendments welcomed from those more erudite in such matters.
 

The Old Ruminator

Well-known member
Here you see the grey " Killas " and the Triassic Sandstone deads from the shaft excavation. Whilst the Sandstone near the surface and ultimately degraded to sand the deeper Sandstone is crystalline and very hard. ( exposed in fracture mid left ).

 

The Old Ruminator

Well-known member
More anon I guess though best to exclude trip references and stick to the more academic. I guess the group thought that here was too public. Maybe thats an inherant problem with the way the forum runs. Most digs are now on other media such as blogs and Facebook Groups. Nothing much here from Mendip or Wales any more. Ones that I look at fairly often are -

Black Sheep Diggers. Great photos and chat on Facebook.
White Rabbit on their own blog
Halloween Rift on their own blog. ( dighalloween )
Mendip Digging Projects. Closed Facebook Group
Individual club Facebook groups

Also what trickles through to journals.
 
Top