Slate roofs are heavy but lasting. You'll see a fair number of them in western Vermont because a unique Slate Belt runs through Castleton, Poultney, Fair Haven, and Granville, New York. A fine museum documenting the great slate era is in Granville, but dedicates itself to the history and lore of slate in both states. A few working quarries remain, along with huge piles of pit tailings. Some day when energy costs are low and the need is high, these may be mined again for their aluminum content. Until then, they're a seemingly endless source of rocks for walls and borders.