Buckingham Slate
Although technically a Phyllite, this product has been used since pre-Civil war times.  Quarried in Buckingham County Virginia with its beautiful black color it is arguably the best black slate in the world.  Unfading in nature and unaffected by acids as well as being impervious to water it will maintain that black color and sheen for the life of the roof.

A.S.T.M.: 1 Samples available.