A vertical vein of slate, situated between Llanberis and Dinorwic, led to the creation of what became the world’s second largest slate quarry. The Dinorwic Slate Quarry was worked for almost 170 years until its closure in 1969, when extraction had become uneconomic and difficult and the business went into receivership. The quarry’s workshop was acquired by the National Museum of Wales and the main quarry is now used as an adventure rock climbing venue and diving venue. I climbed up into the quarry with two photographers from the area, Sian and Albert. It’s not too difficult a climb though it is dangerous in places and the slates slide over…