North Country Semi-Weathering Gray/Green (Sea Green) is a premium quality roofing slate. Gray/Green when quarried, a percentage of these semi-weathering green slate will weather to tones of brown and buff over time. North Country Semi-Weathering Green roof shingles provides moderate color and texture variations while maintaining a primary background color of green. These semi-weathering roof shingles are frequently used as the base color in multi-colored slate roofs. Produced by select Vermont quarries, this slate meets or exceeds ASTM standards as an S-1 rated roofing slate.