Powys Metal Mines Survey
(also known as Castle Rock)
lies in the community of Llanbrynmair in the county of Powys. It is located at Ordnance Survey national grid reference SN84909310.
The mine is recorded in the CPAT Historic Environment Record as number 5942 and this number should be quoted in all correspondence.
Silurian Frongoch & Gwestyn formations. Shales and mudstones. The Dyfngwm lode is the southern branch of the Dylife lode with an ENE strike. Mineralisation includes galena, chalcopyrite and zincblende with quartz and calcite gangues.
A deep adit in the gorge connects with Boundary Shaft on the top of Pen Dylife at SN85219335.
There is a possible hushing channel to the north west of Boundary shaft which descends the southern flank of Y Grug at SN84909331. It would appear to have been fed by breaking a hole in the earthen bank boundary to the north which allowed water following
the boundary ditch to be diverted southward into the prospecting hush. A circular earthen bank at the head of this possible hush may have been a storage pond/hushing dam although it lacks a sluice.
Another possible hushing site lies just below the Roman fortlet of Pen Y Crogbren at SN85709338 where the earthworks of a suspected rectangular hushing dam can be seen next to the old trackway. A narrow prospecting hush channel can be seen on aerial
photographs exiting from the western corner in a southerly downslope direction.
A quarry-like opencast is located near the 1935 processing mill at SN84909315.
Some trials and clearly more productive workings can be seen on the top of the hill which take the form of opencuts, adits, shallow shaft-mound type workings, deep shafts and levels in the base of the opencuts. These workings are clearly attempts to locate
extensions to the Dylife and Dyfngwm lodes. The workings on both of these lodes trend ENE/WSW and run from SN84829326 to SN85789342, a total distance of 1km.
Three levels are particularly interesting as they are probably of great age; all are run-in and one has produced evidence of manual dressing in the form of stone mortarstones buried in the tips. All have a small but constant amount of water exiting from
the buried entrances. They are located at SN85379300, SN84959325 and SN85069333.
Further west along the Clywedog gorge are a number of levels at varying heights in the hillside between SN84789317 and SN84329313.
Castle Rock SN84229310 is probably one of the best natural lode exposures in Wales. At the foot of the rock are numerous trials, a shaft, level and wheelpit.
Tramways lead from the main adit SN84929315 to inclines for carrying the ore down to the dressing floors along the banks of the River Clywedog.
There is a steep track leading eastwards out of the valley onto the top of the hill. This was probably the route by which the ore transport connected with the old coach road on Pen Dylife and later the Machynlleth road in Dylife.
A leat runs into the dressing floors from the Afon Clywedog, traversing the northern side of the valley on its course.
2 waterwheels, stamps and a drawing machine were installed in 1850. In 1856 a steam engine was installed to drive the pump rods in the main adit. In 1858 a 36" condensing engine was added. In 1864 a twin 10" cylinder horizontal engine assisted the pumping
wheel. Also in 1864 a steam traction engine was purchased though it probably saw little use. Two wheelpits and engine bases outside the adit entrance are visible.
At Boundary shaft SN85259334 a 60" Cornish pumping engine was installed. Two ten ton boilers were placed alongside the engine. The iron gudgeon from the balance bob is still visible next to the shaft. The engine house has completely collapsed. The
reservoir for the boilers is located immediately to the west of the engine remains.
In 1861 a 50x6ft winding waterwheel was erected in Dylife at SN86329400 which was drawing at the Old Engine and possibly also the Boundary shaft. The wire winding cable was carried over Pen Y Crogbren partly in a gully which is still visible for a short
distance at SN85789350.
A poorly preserved crusher house is located by the river with two beams for supporting the single pair of crushing rolls at SN84909301.
To the east of this are the substantial concrete and flagstone foundation bases of the 1935 Hirnant Minerals Ltd processing mills SN84879302. These foundations extend from the river and up the hillside to the north. Documentary sources refer to this mill
incorporating the following machinery: a 50hp crude oil engine, 16"x9" stone breaker, screens, granulator, shaking conveyor feeder, 24"x14" crusher rolls, two vibrating screens, a 6 compartement Bull Jig, 2 cleaning jigs, a Ball Mill, 4 concentrating
tables, a 3" centrifugal pump, two 2" pumps and an elevator.
The slurry left over from the ore concentrator was pumped out to a line of seven connected slime pits which run along the south bank of the Afon Clywedog SN84899302.
Other foundation features on the dressing floor are poorly preserved and difficult to interpret.
Two rectilinear enclosures are located very close to the mining area and may be associated with early mining operations although some caution should be noted in this interpretation as they may also be post-medieval agricultural enclosures.
The largest of these enclosures is located at SN84869322 and consists of a large square bank of earth and stone blocks of approx. 1.5m width and surviving to 0.35m in height with traces of a very shallow ditch on three sides and a deeper gulley on the
western side. No obvious entrance was recorded. The enclosure is situated on the rim of the northern side of the gorge above the opencasted area recorded above.
The smaller enclosure is approximately 200yds to the south-west of the large enclosure on the opposite side of a deep gully which descends into the opencast area at SN84809313. The makeup of the earthwork has the same characteristics as the large enclosure
and it may be similar in date and function.
This HTML page is reproduced from the Powys and Clwyd Metal Mine Surveys which were undertaken between May 1992 and December 1993 by Mark Walters and Pat Frost of the Clwyd Powys Archaeological Trust with financial support from Powys County Council, Clwyd County Council and Cadw: Welsh Historic Monuments. Further information about this site is available in CPAT's Regional Historic Environment Record.
Page produced by Rachel Stebbings and Chris Martin.