Pen-yr-Orsedd opened in 1816, owned by William Turner who was also the owner of the nearby Dorothea quarry and the Diphwys Casson quarry in Blaenau Ffestiniog. It was acquired on 1854 by John Lloyd Jones who sold it on to the Darbishire Company, owners of the Penmaenmawr granite quarries, in 1862. The new owners invested £20,000 (equivalent to £1,965,208 in 2016) to expand the quarry, though with limited results; by 1871 the quarry was producing just 500 tons per year. William Darbishire took over direct management of the quarry that year and by 1882 had raised production to almost 8,000 tons.[1]
Pen-yr-Orsedd was one of the major slate producers of the Nantlle Valley. It was the last of the Nantlle quarries to commercially produce slate, closing in 1979.
Narrow-gauge railway museum
Railway enthusiast Rich Morris began collecting narrow gauge rolling stock in 1963,[2] storing many at his home in Longfield in Kent.[3] As the collection grew he sought a more permanent arrangement and in 1976, he came to an agreement with the Festiniog Slate Group to move many of his locomotives to Pen-yr-Orsedd, where he planned to set up a museum to exhibit his collection and tell the story of narrow gauge industrial railways.[2]
With the closure of Pen-yr-Orsedd, The Festiniog Group offered Morris space for his collection at their largest quarry, Oakeley. Morris' collection was moved there in May 1978. Further collections were brought to Oakeley and the Narrow Gauge Railway Centre was opened in the Gloddfa Ganol tourist attraction.
Tramways
In 1862 the quarry was connected to the Nantlle Railway, with 3 ft 6 in (1,067 mm) narrow gauge lines extended to all but the highest levels of the quarry. Most levels of the quarry had both 3 ft 6 in (1,067 mm) gauge and 2 ft (610 mm) gauge trackwork, many with mixed gauge tracks. The Nantlle Railway connection was used up until 1963, while the internal 2 ft (610 mm) gauge lines continued in limited use until the end of quarrying.