Open questions: Caerphilly

Where sources disagree, MineArchive keeps both accounts rather than picking one; where a fact could not be settled, the record says so. 50 such claims on 20 records. All regions.

Abernant Colliery (Argoed)

The Bargoed Coal Company sank Abernant Colliery in 1880. (disputed)

Argoed Colliery

The Argoed and Bedwellty Colliery Company issued a one-pound note at Newport on 9 September 1806. (uncertain)

Black Vein Colliery

The BGS mine-plans catalogue holds a Mining Remediation Authority abandonment plan titled 'Black Vein' (catalogue SWT2914, Spoil Tip, dated 1984); the catalogue gives no location and the plan's details do not clearly tie it to this working, so it may belong to another of the same name. (uncertain)

Britannia Colliery, Pengam

The shafts were sunk from February 1911 to September 1913, and coal raising began early in 1915. (disputed)
Sinking began in 1910 and the first coal was produced in 1912. (disputed)
The North Pit was sunk to 2,181 ft 3 in and No. 2 Pit to 2,202 ft, to the Lower Nine-Feet seam. (disputed)
Shaft No. 1 (downcast) was 615 yards and No. 2 (upcast) 714 yards deep. (disputed)
Each winder had two 2,000 hp motors, either able to run it alone. (disputed)
Each winder had two 1,600 hp DC motors, 3,200 hp in all, fed by Ilgner sets. (disputed)
The colliery closed as a production unit on 8 December 1983. (disputed)
Coflein gives 1989 as the colliery's closure, the year its pumping for Oakdale ended. (disputed)
Coflein records the headframes and major surface buildings as remaining intact. (disputed)
A 1987 photograph's caption describes the colliery as 'now long gone'. (disputed)
The BGS mine-plans catalogue holds a Mining Remediation Authority abandonment plan titled 'Britannia Pengam' (catalogue SWR573, Brithdir, dated 1962); the catalogue gives no location and the plan's details do not clearly tie it to this working, so it may belong to another of the same name. (uncertain)

Bryngwyn Colliery

Bryngwyn Colliery was worked from about 1863. (uncertain)
The colliery started in 1865 or 1866. (uncertain)

Celynen Colliery

Within seven weeks in early 1915, three further men died at Celynen South in separate runaway-dram incidents: timberman Frederick Reed (42) on 2 March, and repairer Walter Bennett (40) and roadman John Vaughan (28, died six days later of his injuries) together later that month. (uncertain)

Darran Colliery

The colliery was sunk in 1868 by the Rhymney Iron Company, with two shafts each reaching the Brithdir house-coal seam at 120 yards. (uncertain)
Until the explosion of 29 October 1909 the mine was considered safe, and throughout its history it had been worked with naked lights. (uncertain)
The colliery employed 272 men in 1908 and only seventy-three by 1918. (uncertain)
The Darran was connected underground to Gilfach colliery; survivors of the 1909 explosion made their way out through the Gilfach shaft, and the rescue party went in that way. (uncertain)
The colliery closed in 1919. (uncertain)

Llanbradach Colliery

Welsh Coal Mines records 2,330 men employed at the outbreak of the First World War. A folklore account gives 2,832 by 1913; the two are not reconciled here. (uncertain)

Llanbradach Quarry

A photograph of 1905 in the National Library of Wales's Martin Ridley Collection shows the quarries in work. No source names an operator or gives an opening or closure date. (uncertain)

Llanover Colliery

Llanover Colliery at Argoed was sunk in 1912. (disputed)
It employed 472 men in 1923, and with Abernant produced 250,000 tons. (uncertain)
A 1923 report gives 434 men employed, producing from the Pontygwaith (Brithdir) seam. (uncertain)

Machen Colliery

Pentwyn closed in 1920 after flooding, with the loss of 150 jobs. (disputed)

Markham Colliery, Sirhowy Valley

Markham Colliery was sunk in 1911 by the Markham Steam Coal Company. (disputed)
The colliery closed in 1986. (disputed)

McLaren Colliery

Abertysswg came into being between 1895 and 1900 through the industrialisation brought by the development of the colliery, the first shaft of which was sunk in 1897. (uncertain)
The pit opened in 1897 and was originally called Pwll Llaca Pit; the McLaren Colliery later re-used the shaft, and it was eventually renamed Abertysswg. (uncertain)
The pit produced steam coal for the steel industry and closed in 1969. (uncertain)
An explosion at the colliery on 3 September 1902 killed seventeen men; the death roll names them with their ages and addresses. (uncertain)
The BGS mine-plans catalogue holds a Mining Remediation Authority abandonment plan titled 'Mclaren' (catalogue SWR953, No. 3 Pit, dated 1957); the catalogue gives no location and the plan's details do not clearly tie it to this working, so it may belong to another of the same name. (uncertain)

Millbrook Colliery

Millbrook was opened around 1825 by a Mr Barnes. (uncertain)

New Tredegar Colliery

1,088 men were employed in 1896 and 1,156 by 1918. For 1923 Welsh Coal Mines gives 1,372 while the Durham Mining Museum's return gives 1,187. (disputed)
The colliery was sunk by the Newport merchant Thomas Powell in 1853, with two shafts each 345 yards deep — one for winding, the other for ventilation and pumping. (uncertain)
The Powell Duffryn Steam Coal Company took over the ownership in 1863 and added two more shafts, the last sunk in 1905. (uncertain)
The pit was forced to close in 1929 when the side of the nearby mountain slid, badly damaging two of the shafts; the site was not cleared until 1965. (uncertain)

Nine Mile Point Colliery

Sources disagree on the date of an earlier serious labour disturbance at the colliery: one places it in 1922 (colliery manager confronted over wage cuts, sixteen miners arrested), another in 1929 (several hundred villagers and miners involved in disorder over blackleg labour). The two accounts may describe different events. (disputed)

Oakdale Colliery

NMRS records a workforce of 3,465 in 1928, while the more widely cited peak figure is 2,235 men in 1938 with output around one million tons a year; the two figures disagree. (disputed)

Rhymney Merthyr Colliery

The same account gives No. 1 as sunk in 1889-90 and, in a separate note, as sunk to the Four-Foot seam in 1892, with No. 2 reaching the Rhas Las in 1897. (disputed)

Risca New Pit

Welsh Coal Mines records the two shafts as sunk in 1875 by Watts, Ward & Co., with coal first raised in June 1878. Wikipedia instead says a new pit with deeper shafts was sunk by 1872. (uncertain)
A Western Mail report of 21 December 1892 stated that the Risca collieries were the first in South Wales to be illuminated by electric light both on the surface and at the pit bottom, and that underground traction was by a complete system of compressed-air haulage. (uncertain)
The 1880 disaster brought the total killed by gas explosions alone at the Risca collieries and the neighbouring Prince of Wales colliery to 591. (uncertain)
A stay-down strike lasting 72 hours and involving 189 miners took place at the colliery in 1935, in protest at the use of non-union workers. (uncertain)
The colliery employed 750 men at nationalisation in 1947 and closed in 1967. (uncertain)

Rock Colliery, Blackwood

The Rock was opened as a level in the early 1800s and is mentioned in the Royal Commission report of 1842, when the owners were the Rock Colliery Company; its shaft was sunk in the late 1880s and used only for raising coal. (disputed)
Rock Colliery worked from 1878 to 1957. (disputed)