... look beauty and eco-friendly blue black slate roofing tiles: 1)Low-calcium,low water absorption and good acid ... color: Black, grey, green, dark-green, blue and rusty yellow Finishing: Both sides natural Features: 1. ... good acid resistance, efflorescence proof, heat-resistance and antifreeze, it is widely used in outdoor roofing, ... or as per client's requirement eco-friendly roof slate/slate for roof