Machen Colliery

Overview

A colliery at Machen in the lower Rhymney valley, begun by Augustus Morgan in the 1840s to fuel his family's limekilns. An explosion killed four in 1858 and the owners went bankrupt in 1860; the workings were taken up again as Pentwyn Colliery, which employed 292 men in 1912 and closed by about 1930.

History

Augustus Morgan began mining coal at Machen in the 1840s. His father, Sir Charles Morgan, owned the local lime quarry, and the coal went to its limekilns. The colliery grew into a group of workings: William's Pit (the downcast), the Old Rock Vein pit and slant, a Rock Vein slant, and a Black Vein furnace pit and slant. On 26 April 1858 a gas explosion killed three men and a boy, John Davies, William George, Isaac Gibbon and George Brimble. At least two of them died of their burns in the weeks that followed, and the Government Inspector's inquiry was adjourned while injured witnesses recovered. At the inquest one of the safety lamps found at the scene was shown to have a faulty clasp for its gauze. Further development stopped when the owners went bankrupt in 1860, and Machen Colliery was abandoned in 1864.

Much of the ground was reworked as Pentwyn Colliery, which was also known as Machen Colliery. The Pentwyn Coal Company opened a pit and a slant, linked by a dramroad down the hillside, to work a lease of 500 acres. The New Pit was 265 yards deep to the Big Rock Vein, 57 inches thick. It worked in spells from before 1875 to 1923. Miss Woodruff owned it in 1888 when work was suspended, and W. Lewis in 1893. Employment rose from 7 in 1896 to 292 in 1912.

By 1917 the Pentwyn Glamorgan Colliery Syndicate worked it, and in 1918 Pentwyn Black Vein Collieries Ltd employed 101 men under T. R. Williams. The Ashburnham Steamship and Coal Company followed. The pit was abandoned before 1923, when the slant employed 197 men on the Big, Black and Brass seams. One account has the colliery closing after flooding in 1920 with the loss of 150 jobs. Only seven men remained in 1930, and work had ended before 1932.

Geology

Coal Measures on the southern outcrop of the coalfield: the Big Rock Vein (57 inches at the New Pit), Little Rock, Black, Big, Brass, Sun, Fork and Hard seams.

Workings

William's Pit (downcast), the Old Rock Vein pit and slant, a Rock Vein slant and a Black Vein furnace pit and slant; later Pentwyn New Pit (265 yards to the Big Rock Vein) and a slant up the hillside joined by a dramroad, with Pentwyn level and drift.

Closure

The first colliery stopped after its owners' bankruptcy in 1860 and was abandoned in 1864. Pentwyn's seams were abandoned in stages (Little Rock 1887, Big Rock and Black 1916, the rest 1923); the pit had gone by 1923, and the slant worked on with a handful of men into 1930.

What remains

Unknown.

Redevelopment

Unknown.

What's uncertain

Points where sources disagree or the record could not be settled; both accounts are kept. All open questions in the archive.

• Pentwyn closed in 1920 after flooding, with the loss of 150 jobs. (disputed) ¹

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• Augustus Morgan began mining coal at Machen in the 1840s to supply the limekilns of his father, Sir Charles Morgan. ¹
• A gas explosion on 26 April 1858 killed three men and a boy. ¹
• Men burned in the 1858 explosion died in the following weeks, and the Government Inspector's inquiry was adjourned. ^2,3
• Machen Colliery was abandoned in 1864. ¹
• Pentwyn Colliery, also known as Machen Colliery, had a pit 265 yards deep to the Big Rock Vein. ⁴
• The Pentwyn, Machen, William's Pit, furnace pit, Garn drift and Coed-y-cefn workings are recorded on one set of plans. ⁵
• Pentwyn closed in 1920 after flooding, with the loss of 150 jobs. (disputed) ¹
• Pentwyn's slant employed 197 men in 1923 and seven in 1930, closing before 1932. ⁴

Photographs & further reading

Sources

1. (secondary) Welsh Coal Mines: Machen (Old Machen (Pentwyn) Colliery) — Welsh Coal Mines
2. (primary) 'Machen', Monmouthshire Merlin, 8 May 1858 — Welsh Newspapers Online (National Library of Wales)
3. (primary) 'Machen. The late colliery explosion', Monmouthshire Merlin, 15 May 1858 — Welsh Newspapers Online (National Library of Wales)
4. (secondary) Welsh Coal Mines: Pentwyn and Rudry collieries — Welsh Coal Mines
5. (primary) BGS / Mining Remediation Authority mine plan: PENTWYN MACHEN, WILLIAMS PIT, FURNACE, GARN DRIFT, COED-Y-CEFEN LEVEL — British Geological Survey

Record created: 10 October 2026 · Last researched: 10 October 2026