Gleision Colliery

The Tarenni Colliery (Welsh: Gloddfa Tarenni) and its associated workings, are a series of coal mines and pits located between the villages of Godre'r Graig and Cilybebyll located in the valley of the River Tawe, in Neath Port Talbot county borough, South Wales.

Primrose Colliery was developed from the mid-1800s, close to the village of Rhos. After the disaster of 1853, it was redeveloped as the New Primrose Colliery, owned by Sir Ralph Howard, and by 1896 employed 307. It closed in the early 1900s, but from 1908 was revived as a pumping station for the Tarenni Colliery.

The major coal seams are located close beneath the valley floor, but mean accessing steeply declining seams which run in high geological fault structures, running directly under the River Tawe. This makes the coal easily accessible, but also dangerous to extract.

The first drift mine workings occurred in the late 1800s, at a site referred to at the time as the Tirbach Slants. The Pwllbach Colliery Company started development in 1898 of two slants, main and reverse, and after a series of lease changes which reverted the lease to the Pwllbach Colliery Company, production started in 1905. After the company collapsed into administration in 1924, the lease was taken over by the Pwllbach, Tirbach & Brynamman Anthracite Collieries Ltd, which in 1938 became Henderson's Welsh Anthracite Collieries Ltd.

These companies all worked the same seams: Big (abandoned 1939); Peacock (or Brass); Middle and Lower seams. The workings employed 651 in 1936, the height of its production. The site was closed from February 1940 due to geological difficulties, with 500 men given notice in January 1940. At this time during World War II, labour was expensive, so it is likely that economics also played a large part in the decision to close. The mine reopened in May of that year, but had been completely abandoned by December 1940.

The site then became a disposal centre for extract from the main Tarenni Colliery, and after nationalisation, the National Coal Board used it as a training site.

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