Alpina roofing slate has virtually no unstable minerals such as pyrites, graphite, carbon and un-oxidised irons and will withstand the most severe weather conditions: it is unaffected by sunlight, ultraviolet light and even acid rain. Laid correctly Alpina roofing tiles will last the lifetime of the building and is ideal for use on any major project including supermarkets, schools, city offices and prestige homes.
http://www.cembrit.co.uk/roofing/natural-slates/alpina/