Coslet Colliery

Overview

A Dowlais Iron Company level at Dowlais that fed the works' furnaces with coal and ironstone until the company gave up its feeder levels together in May 1924.

History

Coslet Colliery was used by the Dowlais Iron Company to feed its iron works, and was abandoned in May 1924. It formed part of the wider "Dowlais Collieries" complex, the umbrella name for everything worked for the Dowlais Iron Works, which comprised Coslet alongside Black Ball, Blaen Dowlais, Brewhouse, Buxton's, Carno, Cwmcenol, Morgan's, Pant-y-Waun, Penyard, several Penydarren pits, Pen-yr-Heol, Price's, Rhas Las, Tyla Dowlais and Vanwain — all worked for coal and ironstone and abandoned together in that same month. Coslet appears on two surviving Mining Remediation Authority plans: the 1924 abandonment plan of the Dowlais water levels, and a plan of the Dowlais, Gwaun Court and Penydarren levels showing the Gellideg (Lower Four Feet) coal and ironstone measures from the Black Pin to the Rosser.

Geology

Plans of the Dowlais levels that include Coslet record the Gellideg (Lower Four Feet) coal and a run of ironstone measures — Black Pin, Black Ball or Spotted, Red and Yellow, Blue, Lumpy, Pins and Purple, and Rosser — though they do not say which of these Coslet itself worked.

Workings

A level worked for coal and iron, part of the wider Dowlais Collieries complex.

Closure

Abandoned in May 1924 with the rest of the Dowlais Collieries complex, the umbrella working of which it formed part.

Recorded claims

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

• Used by the Dowlais Iron Company to feed its iron works, abandoned in May 1924. ¹
• Named among the pits making up the wider Dowlais Collieries complex, all worked for coal and ironstone and abandoned together in May 1924. ²
• Owned by the Dowlais Iron Company throughout its documented working life. ²
• Coslet appears on the 1924 abandonment plan of the Dowlais water levels (coal and ironstone) and on a plan of the Dowlais, Gwaun Court and Penydarren levels recording the Gellideg (Lower Four Feet) coal and ironstone measures from the Black Pin to the Rosser. ^3,4

Photographs & further reading

Sources

1. (secondary) Small collieries of the Dowlais Cwmbargoed & Penydarren areas — Northern Mine Research Society
2. (secondary) Dowlais Collieries — Northern Mine Research Society
3. (primary) BGS / Mining Remediation Authority mine plans catalogue: Dowlais (water levels): Black Ball, Blaen Dowlais, Brewhouse, Buxton's, Carno, Coslet, Cwmcenol, Morgan's, Panty Wain, Penyard, Penydarren Nos 2, 4, 7, Pen-yr-Heol, Prices', Rhas-Las, Tyla Dowlais, Vanwain — British Geological Survey
4. (primary) BGS / Mining Remediation Authority mine plans catalogue: Dowlais, Gwaun Court, Penydarren 1-7, Coslet, T P Banwain, Tyla Dowlais and other levels — British Geological Survey

Record created: 15 September 2026 · Last researched: 16 September 2026