North Country Semi-Weathering Gray/Black (Strata Gray) is a premium quality roofing slate of varying shades of gray with numerous inclusions of black and dark gray. A small percentage of these slates will weather to tones of brown and buff over time. North Country Semi-Weathering Gray/Black (Strata Gray) is produced by select Vermont quarries and meets or exceeds ASTM test requirements as an S-1 rated roofing slate.