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It was the largest quarry in the area, employing 200 men and producing 5,000-6,000 tons of finished slate a year. A group of quarrymen led by John Robinson, William Owen and John Jones purchased Dorothea from Turner for £3,000 - equivalent to £325,276 in 2016. They renewed the lease of the quarry in June 1851.
Slate mines are found around the world. 90% of Europe's natural slate used for roofing originates from the Slate Industry in Spain. [1] The major slate mining region in the United Kingdom is the Lake district, with Honister slate mine being the last working slate mine, the only producers of the world famous Westmorland greenslate.
Slate extracted from the narrow vein at Aberllefenni is deep blue and extremely hard and dense. It resists fine splitting, so most of the mines' product was large cut slabs rather than split roofing slates. Foel Grochan mine consists of eight near-horizontal tunnels at approximately 60 feet (18.3 m) vertical separation.
The MOD is significant when planning dives using gases such as heliox, nitrox and trimix because the proportion of oxygen in the mix determines a maximum depth for breathing that gas at an acceptable risk. There is a risk of acute oxygen toxicity if the MOD is exceeded. [1] The tables below show MODs for a selection of oxygen mixes.
The Welsh Slate Company's Lower Quarry mine extended directly beneath that of the Middle Quarry, its progress was limited by the speed with which the Middle Quarry progressed, because both were working the same vein of slate. But the Middle Quarry was mining more slowly than the Welsh Slate Company desired, so the latter had taken the dangerous ...
The Penrhyn quarry is a slate quarry located near Bethesda, North Wales. At the end of the nineteenth century it was the world's largest slate quarry; the main pit is nearly 1 mile (1.6 km) long and 1,200 feet (370 metres) deep, and it was worked by nearly 3,000 quarrymen. It has since been superseded in size by slate quarries in China, Spain ...
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Llechwedd quarry (Welsh pronunciation: [ɬɛχˈwɛð]) is a major slate quarry in the town of Blaenau Ffestiniog, north Wales. At its peak in 1884 it produced 23,788 tons of finished slate per year and had 513 employees. It continues to produce slate on a limited scale and is the location of the Llechwedd Slate Caverns tourist attraction.