Monday, 15 October 2012

Nantmor Mine

Some of the fascinating remains of the Nantmor Copper mine, in Cwm Bychan. Starting point: Nantmor car park, grid ref: SH597462
 

Above: one of the remaining pylons for the aerial ropeway built in 1927 to carry ore from the upper end of Cwm Bychan, down the valley to where the Welsh Highland Railway had laid a siding in. Before this, ore was transported along the Afon Glaslyn, a small quay having been built in the mid 18C. In those days, the river was tidal -before William Maddocks built the cob at Porthmadog.

Four pylons from the valley's original ore-transporting ropeway are still in existence, along with the concrete bases of others. Historical accounts show that the system wasn't a complete success, with buckets often said to hit the ground, spilling their loads. The remains of the ropeway add to the other features seen across the whole valley, with adits, spoils heaps and buildings signalling back to the area's industrial past. It's also an internationally scarce wildlife habitat. The type of heathland seen here can only be found in a few of the western coastal areas of Europe. This area is home to insects and butterfiles such as the grayling butterfly and birds including the wheatear and whinchat.


  The corroded remains of the sheave and supports at the upper terminus of the ropeway. Below: the sheave with the tip in the background. The traveller wheel and tub rider support looks, to my eye at least, like a rusty cat...


Above: The less-than inviting mouth to the flooded adit.

Above: The NE crosscut adit showing the hanging planar wall to the right with yellow sulphides and mineralisation of the quartz. This is in a dryer area of the mine. The entrance drive is wet up to thigh height for a good way, before rising slightly to a large stoped-out area.



Above: The adit, which drives in for 70 soggy metres.


Light comes in from the stoping, which breaks out to bank 20 metres above. Deep water again, here!


The grotto in the crosscut, showing plenty of mineralisation from Chalcopyrites in the walls. The rock seems to be a kind of quartzy breccia. Here and there along the adit some drilling has gone on to chase apparent mineral veining.


Looking up to the stoping. For some interesting photos taken from within the stoping, have a look at  Graham Steven's shots of the mine, here at Geotopoi..

The NW crosscut towards the forehead was driven into barren rock, the mineralisation rapidly disappears along with the quartz vein, with only sulphides leaching out, making the water a vivid orange colour.

  Gypsum crystals forming along the footwall- from a video still by Petra.  Here are some further snaps of the walk up to the mine:

A gnarled Oak on the way up from Nantmor to Cwm Bychan.

.Clouds above the Moelwynion, seen from the path. Lastly, a rustic timber seat which was gratefully utilised during our walk to the mine:





Although I show photographs here from our exploration underground, I must stress that the mine is extremely dangerous and any exploration should only be attempted by those experienced and properly equipped.

2 comments:

geotopoi said...

Interesting report, Iain. Good to see the inside of the adit. Those ropeway pylons are wonderful relics!

Iain Robinson said...

Thanks, Graham. Ta also for the tip-off about this location.

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