Gurnos Colliery

Overview

An anthracite colliery of three closely spaced slants at Ystradgynlais in the upper Swansea Valley, opened about 1900 by the Gurnos Anthracite Colliery Company on the site of the older Wernplemis working, and driven at 1 in 3 to a Big Vein up to 90 inches thick. It employed up to 300 men, suffered a shotfiring explosion in 1909 that killed two, and passed to Amalgamated Anthracite before closing in 1928, after which it was kept for pumping.

History

A mine called Wernplemis or Wernplumys worked here before 1858 and closed in 1874; its slant was later Gurnos No. 1. Gurnos Colliery was opened about 1900 by the Gurnos Anthracite Colliery Company of Ystradgynlais, a small concern outside the coal owners' association, and was served by the Neath and Brecon Railway. It comprised three slants close together: No. 1 to the north, a return in the middle and No. 2 to the south, driven down at 1 in 3 to the Big Vein, here 78 to 90 inches thick. In 1908, under Daniel Davies, it employed 183 men underground and 30 at the surface. At about 5 am on 17 December 1909 a shot fired in the Big Vein ignited gas, killing two men and burning three (see Disasters, below). Manpower was 286 in 1912 and rose to 300 during the First World War. In 1918 D. Jeffreys managed 186 men underground and 31 at the surface, and the company also held the neighbouring Diamond Colliery by 1923. Gurnos was one of the first collieries taken into Amalgamated Anthracite Collieries, in 1923. It abandoned the Four Feet seam in November 1922 and the Peacock or Brass seam in August 1928; Welsh Coal Mines dates closure to 1928, after which the colliery was kept for pumping until 1944, while NMRS records 250 men as late as 1934 and says only that it closed before 1947.

Geology

Worked the Big Vein anthracite, 78 to 90 inches thick, and the Four Feet and Peacock (Brass) seams.

Geological setting: Sedimentary Beds and Seams (historical documentary reference)

Workings

Three slants very close together, driven at 1 in 3: No. 1 (originally Wernplemis) to the north, the return in the middle and No. 2 to the south.

Closure

Welsh Coal Mines says it closed in 1928, when the Peacock or Brass seam was abandoned, and was retained for pumping until 1944. NMRS gives 250 men in 1930 and 1934 and says it closed before 1947. No reason is recorded.

What remains

Unknown.

Unknown.

Redevelopment

Unknown.

Nearby mines

• Yniscedwyn Colliery — 1.0 km NE
• Tirbach Colliery — 1.4 km W, Neath Port Talbot
• Pwllbach Colliery — 2.1 km W, Neath Port Talbot
• Ystalyfera Colliery — 2.4 km SW, Neath Port Talbot
• Gilwen Colliery — 2.5 km W, Neath Port Talbot

Straight-line distance, within 15 km. Show on the map.

Disasters & major incidents

• Gurnos Colliery Explosion, 1909
  17 December 1909 · Explosion · 2 fatalities
  A shot fired at the face just before 5 am ignited gas and engulfed the men nearby in flames, fatally burning the collier who had prepared it and burning the fireman. A repairer working further off, unhurt by the blast, set off towards the return airway rather than out of the mine and was later found a few yards away, overcome by gas.

Recorded claims

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

• Gurnos opened in 1900 with three slants close together; the No. 1 slant was originally Wernplemis (Wernplumys), in existence before 1858 and closed in 1874. ¹
• It consisted of two slants driven down at 1 in 3 to the Big Vein, 78 to 90 inches thick, worked by the Gurnos Anthracite Colliery Company and served by the Neath and Brecon Railway. ²
• In 1908 it employed 183 men underground and 30 at the surface under Daniel Davies; in 1918, 186 underground and 31 surface under D. Jeffreys. ^2,1
• It was one of the first collieries to come under Amalgamated Anthracite Collieries in 1923. ^2,1
• It abandoned the Four Feet seam in November 1922 and the Peacock or Brass seam in August 1928, when it closed, and was retained for pumping until 1944. (disputed) ¹
• It employed 250 men in 1930 and 1934 and closed prior to 1947. (disputed) ²
• The BGS mine-plans catalogue holds Mining Remediation Authority plans titled 'Gurnos or Wenplemis Slants' and a combined plan of Diamond and Gurnos or Wernplemis slants. ³

Photographs & further reading

Sources

1. (secondary) Gurnos, Ystradgynlais (with Gwaunclawdd, Diamond and Ystradgynlais collieries) — Welsh Coal Mines
2. (secondary) Gurnos Colliery — Northern Mine Research Society (Ray Lawrence)
3. (primary) BGS / Mining Remediation Authority mine plans: GURNOS OR WENPLEMIS SLANTS — British Geological Survey / Mining Remediation Authority

Record created: 16 September 2026 · Last researched: 16 September 2026