I am currently working my way through Mining Journal - I found this intriguing reference (completely irrelevant to my research) on page 408 of the 1850 volume:

"CWM ORTHIN SILVER - LEAD MINES.
Besides the above slate properties, a very promising silver - lead mine has been opened on a good lode of ore, on the north eastern verge of one of the mountains of Rhossyd, called Cwm Orthin........ about 5 fathoms of shallow levels, &c. have been driven, from which some tons of ore are now on bank, that produce 25 ounces of fine silver per ton......."


Did this amount to anything or was it purely a trial? Does anything remain?

"CWM ORTHIN SILVER - LEAD MINES.
Besides the above slate properties, a very promising silver - lead mine has been opened on a good lode of ore.....
.....25 ounces of fine silver per ton......."


Did this amount to anything or was it purely a trial? Does anything remain?

Blimey! I'm leaving now, I'll see you all down there in an hour! Bring your picks!

Never heard of this one, although it would be interesting to find out what and where exactly the trials were....at a guess you would think further up the valley, looking at the terrain/rock types. I'm not very well up on the history of Cwmorthin, others know far more than I do, but I imagine it was another "exaggerated" claim....there were a few well known scams over the years.

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Quite a few metalliferous lodes in the vicinity - the one worked as Moelwyn is an obvious example. Another lode was cut by the road up to the Stwlan dam - this one not apparently worked. Found a section of an 8-inch rib of galena/sphal/chalcopyrite in the debris there many years ago. Pyrrhotite pyrite and arsenopyrite also present - rather typical assemblage for the Snowdon Caldera and surroundings. Such occurrences stretch from the Carneddau to Nantlle, down to Porthmadog, across to east of the Manods and back to the Carneddau.

The mineralisation is always recrystallised due to the slate-belt deformation, which distinguishes it from the stuff of the Llanwrst Orefield - again a lot more extensive - which overprints both the Caldera mineralisation and that of the Dolgellau gold belt by forming coarsely crystalline cross-cutting veins carrying calcite, marcasite, sphalerite, galena, quartz etc.

How the Caldera and gold belt mineralisation are related, if at all, is unclear. Some similarities but some differences. Both pre-date the deformation, whereas the Llanwrst stuff post-dates it. High time an exhaustive Pb isotopic study of the whole lot was undertaken!

...others know far more than I do....

Told you someone would be along soon who knew more than I do! The metalliferous lodes are quite common and obvious....I can usually spot locations by the type/colour of rock in the spoil heaps.
Would be interesting to know where the lode is/was...25 ounces / ton is a nice number...any idea if they meant silver-copper or silver-lead ore or some other mix?

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...others know far more than I do....

Told you someone would be along soon who knew more than I do! The metalliferous lodes are quite common and obvious....I can usually spot locations by the type/colour of rock in the spoil heaps.
Would be interesting to know where the lode is/was...25 ounces / ton is a nice number...any idea if they meant silver-copper or silver-lead ore or some other mix?

The East Cornwall silver mines which were active in the 1830s were claiming 200 - 300 ozs. per ton which makes 25 sound pretty insignificant. That said most of the East Cornwall mines were, to a greater or lesser extent, scams, so how accurate that figure was is debatable.

One also needs to consider what the measure means does the ton refer to lode material as raised or does it refer to the dressed ore?

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or does it refer to the dressed ore?

Typical % age of Silver in ore these days would be circa <0.1%? Someone correct me here?
So 25oz per ton of ore would be "about right, leaning towards good"....highly technical summation eh???
200-300 seems excessive....let's wait 'til a mining Engineer with Silver mine experience comes along to guide us... I was only ever shafts and tunnels! :lol:

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When I worked at Gwynfynydd, some of the galena/sulphides ran at 300 oz/t of silver.

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When I worked at Gwynfynydd, some of the galena/sulphides ran at 300 oz/t of silver.

Dressed ore, following removal from waste rock? Wow!
I'll put the pick away then....we'll never get rich at 25 oz/ton!

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The tetrahedrite from the Darren Mines of Central Wales (visible in hand specimen) runs 15-20% silver. That's what gave those mines their high silver content, as it is also abundant as inclusions in galena. It also occurs as inclusions in galena at Gwynfynydd, Tyddyn Gwladys and certain other mines of the gold-belt, along with pyrargyrite, hence the high Ag values reported above. I've not recorded any from the Snowdon Caldera lodes, but that could simply be down to the fortunes of sampling.

The Merionethshire six-inch map sheet III.SE (surveyed 1887-8) shows a 'level' at SH665465 which might be a candidate. (It's not shown on the current 1:10,000 map.)

Dave

Google Earth shows it might be worth a look.

Chris.

The Merionethshire six-inch map sheet III.SE (surveyed 1887-8) shows a 'level' at SH665465 which might be a candidate. (It's not shown on the current 1:10,000 map.)

Dave

That's where I imagined it to be, on that side of the valley, looking at terrain and rock type, although perhaps I imagined it would closer to Plas Cwmorthin. I'm going up there on Sunday so stand by for news of the new "Silver Rush".

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FWIW, the North Pennine orefield averaged 4-8oz Silver per ton smelted Pb, with values frequently as low as 1 or 2 oz/ton, and exceptionally 40oz/ton. I'd bet anyone getting 25oz/ton would be well chuffed!

MARK

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Has anyone checked this out on the ground yet?