They have Identified one orebody in the Great Lst. which extends at least 100m along the strike of the Scaleburn vein extending up to 60M away from the vein and a thickness of over 10M over much of it's area. I don't know what the average grade was but individual grades on some of the slides shown were over 10%.

The next stage in the project is to try to discover the extent of the mineralisation in the Great Limestone on all four of the veins in that area and to deepen some of the holes to investigate the limestones immediately above and below the whin sill because their original hole No 3 found zinc at these horizons.

They are currently drilling out at Wellhope

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Interesting that they feel that Anglo Austral missed some ore here, in the Nentsberry mine. I would have thought of all the ore- field this was the one area that had been drilled properly. Dunham quotes the zinc reserves here, mixed with witherite and hence left alone!,
As Ritch has already pointed out it looks as if they have found bits of ore left by the old- man and some evidence of orebodies in lower strata.
Unless they hit something big I am sure they will not have enough ore to proceed.
Has there been any indication of how many holes are expected to be drilled this year?

t looks as if they have found bits of ore left by the old- man and some evidence of orebodies in lower strata.
Unless they hit something big I am sure they will not have enough ore to proceed.
Has there been any indication of how many holes are expected to be drilled this year?

Peter Tyler's comment was that the old men had only taken about 20% of the available in the Great Limestone.

Didn't get a number of holes but they are carrying on, presumably with just the single rig. I'll ask next time I see him.

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This current phase of drilling is due to be completed in June, id imagine we will hear then, Mincos immediate plans.

gNick's report of a statement of Peter Tyler that the old man only discovered 20% of the Great Limestone orebodies I feel must be one of the most optimistic on record!
Most of us have seen the Dunham plan of the horse- levels in the Coalcleugh/Nenthead area, and come to the same conclusion as he did that most of the GL strata has been explored.
Indeed Dunham suggested that prospecting of the Killhope water-shed was, in his opinion the best area to look for new ore-bodies, and having seen the assays of the veins discovered it was pretty disastrous. He did suggest though that ore-bodies might be found in the Melmerby Scar Llimestone, which is what I thought was the main aim of Minco's drilling programme.

If the recent reports from the nenthead meeting are as bad as they seem, would Minco not be better pulling out and cut their losses. It seems a pipe dream going by reports on here and the silence from minco is deafening.

If the recent reports from the nenthead meeting are as bad as they seem, would Minco not be better pulling out and cut their losses. It seems a pipe dream going by reports on here and the silence from minco is deafening.

Probably not until they have pumped up their share price sufficiently to make a tidy profit from some spurious announcement! 😉

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With all due, they have discovered the ore in a more disseminated form off the vein line. Since the miners & Dunham didn't do core drilling how would they know it was there?
From what I gather they were more interested in the more concentrated ore in the vein & VM's plant probably wasn't up to processing it anyway.

The presentation was an update on how things were progressing and the status was looking good enough to carry on spending (not inconsiderable) money on the drilling.
If they were trying to bump up the interest to make a fast buck, they did it in a very strange way.

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gNick. You are quite right. Everyone should look at p 49 of Minco's AGM presentation that was used as the basis of Roger Bade's article for the Friends of Killhope. The size of the lower grade aureole (shown in white) around the old workings (shown in pink) is most impressive and if there are similar deposits elsewhere along the veins then we are into a new era in the Pennines. Also look at the photographs of the cores and ask yourself would the Old Man have considered working ground like this.

The presentation is at

http://www.minco.ie/pdf/Minco%20Presentation%202013%20AGM.pdf 

but watch out it is 20 Mb long!

Dave Greenwood

I have not looked at Minco's optimistic plan, i do not see, unless they have cored across a Vein structure how they can up with such an interpretation. Unless I am very mistaken the drillling rig they are usung is a simple vertical one with no horizontal accessories..
During the war a large flotation plant was set up to process ore from the dumps, with the possibility of working low grade ore in the mines.
It presumably was not economical then, and as I have stated previously unless they find a large deposit, of decent metal values this project looks highly speculative.

Minco are not talking about vein mineralisation. Instead they think they have found evidence for a massive low grade Zn/Pb orebody that extends for up to 50 m from the vein and in places extends over the full thickness of the Great Limestone. Their cross section on p 49 of their AGM presentation shows that CA006 intersected 5.15 m of this material around an old stope at about the horizon of the Middle Flat some 50 m from the vein. This analysed at 6.59 % Zn and 1.44% Pb over the 4 m length that was still in situ. CA008 sited about 25 m from the vein passed through an old stope at the horizon of the High Flat and then through 13.85 m of ground shown on the diagram as being 12% Zn + Pb although elsewhere (p 34) this same section is shown as 12.05 m at 7.65% Zn and 0.79% Pb - so there is a slight discrepancy there. The diagram indicates that both boreholes were vertical. Minco’s comment on this (p 45) is:

“The stopes intersected in CA006 and CA008 clearly demonstrate that past producers mined selectively from within the overall mineralised system and that the bulk of the system could remain in situ.”

Minco have used these two intersections to suggest there is an orebody in the Great Limestone with a cross sectional area of around 700 m2. The map on p 32 shows these two holes were drilled on the NW side of Scaleburn Vein. The photographs of the cores (pp 35-44) show the mineralisation to consist of a limestone breccia recemented with tan coloured sphalerite and straw coloured ankerite/siderite. This sort of material would have been very difficult to treat at the Krupp gravity mill run by VMZ because of the closeness of the SG of these minerals, which is also why the WWII 1,000 tpd flotation plant was able to recover so much Zn from the VMZ tailings that ran at 3.4% Zn and 0.4% Pb (Dunham’s figures).

I can’t think of anywhere else in the orefield where there is such extensive mineralisation up to 50 m from the vein that also extends through the full thickness of the Great Limestone, which is why I am saying that Minco have found something entirely new. It remains to be seen whether or not there is enough of this sort of material at the right sort of grade to be economic. Also as Minegeo has pointed out there is a question of how much MgO is present. But the results so far are very encouraging and the results from the recent drilling at Coalcleugh and now at Wellhope should be very interesting to say the least.

Dave Greenwood

That stuff does look interesting although the core samples appear to be of epigenetic, not syn-sedimentary, Pb-Zn mineralisation. Massive replacement flats extending away from the vein system possibly....

Peter was asked whether they were flats and he thought not though I can't remember his terminology.

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Sopwithfan - In all fairness and in the real world you cannot call 50m width "massive" and the thicknesses are still very thin. Compare with a modern mine such as Navan where the mineralization extends for several kilometres down-dip and over vertical thicknesses of up to 100m with grades averaging 10% Zn+Pb. So 50m at marginal grades has some way to go yet.

Can we also only use the term "orebody" once it is confirmed to be an economic proposal, until then it is just mineralization.

Minco may find some small replacement mineralization adjacent to vein feeders but it is categorically NOT Irish type and they need to start hitting better intercepts than those to date to have their sights on a minable deposit.

Good luck to them but it would, pethaps, be better if they said their target was MVT-type mineralization on a block and NOT to mislead by claiming its Irish-type (It clearly is'nt).

Sopwithfan - In all fairness and in the real world you cannot call 50m width "massive" and the thicknesses are still very thin. Compare with a modern mine such as Navan where the mineralization extends for several kilometres down-dip and over vertical thicknesses of up to 100m with grades averaging 10% Zn+Pb. So 50m at marginal grades has some way to go yet.

Can we also only use the term "orebody" once it is confirmed to be an economic proposal, until then it is just mineralization.

Minco may find some small replacement mineralization adjacent to vein feeders but it is categorically NOT Irish type and they need to start hitting better intercepts than those to date to have their sights on a minable deposit.

Good luck to them but it would, pethaps, be better if they said their target was MVT-type mineralization on a block and NOT to mislead by claiming its Irish-type (It clearly is'nt).

Ah ha the voice of reason, I would agree with all these comments, I think some people are getting a little bit ahead of themselves, we have seen this kind of thing before, such an example being the Parys Mountain "orebody" where no extraction has taken place to date! Brings back memories though, as my dissertation was on MVT mineralization! :lol:

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Minegeo. I agree "massive" was a bad choice of word. What I had in mind was "compact" or "solid" etc. in other words not full of lough holes lined with recognisable crystals of blende or galena as in the conventional NPO flats. I also agree that it is far from being an orebody in the strict modern sense of the word.

All I am saying is this kind of mineralisation is new to the NPO and as Roger Bade has pointed out in his Friends of Killhope article out it will eventually need to be explained in terms of the overall geology. In particular it goes against the long held tradition of that replacement mineralisation in the Great Limestone is limited to the three flat horizons that became the principal exploration targets for the Old Man. An idea that goes back at least to Westgarth Forster and runs through all the writings of Sopwith and Wallace etc. The Minco work now seems to suggest that it might affect the entire thickness of this unit even at a distance of 25 m from a known vein - admittedly on the basis of one borehole at present.

Dave Greenwood

Anyone who has looked at limestone deads, from the Nenthead flats & Veins, which have been sectioned using a diamond saw, could not miss the small amounts of visible zinc and lead in it.
Clearly this low grade mineralisation will continue into the flat & Vein walls, but unless lateral diamond core drilling is carried out I cannot see how you can figure out you have the amounts of mineralised ground suggested.
One thing is fairly certain this mineralisation is present only in the G.L. and there is no suggestion of a vertical extension, which has already been suggested is completely different to Tara.
Perhaps Minegeo will know how this compares to the Lisheen deposits?

John

I would say that it is nothing like Lisheen / Galmoy / Pallas Green. These are all Irish-type lying within a rapidly subsiding shallow basinal setting (unlike the NPO which is on a horst-like block). The style of mineralization is also completely different. The Lisheen / Galmoy / Pallas Green mineralization occurs at the immediate contact of the Waulsortian mudbank limestones with the underling Argillaceous Bioclastic Limestones (similar setting to Tynagh and Silvermines). The mineralization is dominated by finely banded schallenblende beige, brown and cream sphalerite with subordinate galena and pyrite. Minor deeper seated style mineralization comprsiong chalcopyrite, sphalerite, galena and silver-copper sulphosalts often are seen in replacements adjacent to synsedimentarily active feeder faults.

None of these characteristics is seen in the NPO and the age of mineralization both relative to sedimentation and in absolute terms, and the source rocks are completely different as indicated by isotopic characteristics.

In short the NPO has virtually no similarities to any of the Irish deposits.

The style of mineralization they have intersected really should be of no surprise. The zinc "core" along the Burtreeford Disturbance shows higher temperatures than the marginal parts of the NPO suggesting a central and thus warmer zone of mineralization which could explain the difference in styles and gross chemistry of the GL and other replacements. They are, of course, all proximally relaed to the feeder vein systems which may have ultimately been filled by later (cooler) styles of flourspar dominat mineralization.

Hope this helps ?

That makes sense to me for sure. Metasomatic alteration of a carbonate sequence is going to vary according to the temperature, pressure and chemistry of the fluids doing the attacking. The drillcore is interesting because some of those images also suggest hydraulic fracturing/brecciation was part of the process - quite a few classic examples of matrix-supported breccias in there. You could be seeing hydraulic jacking-apart of prominent bedding-planes in the Great Limestone - a bit like the once-famous Van Flats in Central Wales (which were not replacement-flats). One way to test this hypothesis would be to ascertain whether the Great Limestone is anomalously thick in the area in which the mineralisation has been discovered....

The Great Limestone Cylcothem was studied by Brian Hodge for his PhD Thesis at the University of Durham. See Hodge, Brian Leslie (1965) The great cyclothem northern England, Durham theses, Durham University. Available at Durham E-Theses Online:

http://etheses.dur.ac.uk/9000/ 

Note this is 23 Mb long.

Brian worked under the supervision of KCD and made full use of old mining records and it unlikely that they would have missed any unusual features such as the GL being anomalously thick in relation to the mineralisation. Dunham (1990) has further details of the Great Cyclothem in a table on p 29 that includes references to the mines in the Nenthead area where the thickness of the GL varies from 59 to 67 ft (18-20 m).

Perhaps more significant is the slight N-S trending anticlinal axis that is superimposed on the overall Teesdale dome just to the east of Nenthead in the Minco exploration area. Wallace considered this structure to have had a major influence on mineralisation - although he did think it came down from above and was related to present ground levels!

Dave Greenwood.