There are many types of roofing slates in the New England area. Vermont green slates, Black Monson slates, Mottled purple slates.The Black Monson slates have a life span of 200 years or more. Mottled purple and Vermont green slates have roughly 150 year life span. The Black Monson quarry shut down sometime around 1915 and all repairs to roofs are used with salvage slate shingles. The Vermont slates and Mottled purple slates we can still buy new for any repairs.