Welsh Slate benefits from a number of highly practical properties making it an exceptional Roofing Slate. It is extremely durable, unaffected by normal extremes of temperature and is highly resistant to acids, alkalis and other chemicals. It retains its natural colour, even in UV light and is impermeable to water. Welsh roofing slate from Penrhyn, Ffestiniog and Cwt-y-Bugail quarries are known to produce the finest roofing slates in the world.