slate/grey roofing slate pencil 1.Direct supply from factory 2.High quality,prompt deliver 3.competitive price Slate is a fine grained metamorphic rock formed from clay, sedimentary rock shale, and sometimes quartz. Slate is a hard stone but brittle which will break easy into smooth slabs. The availability of slate in various colors including gray, black, brown, green, red, or purple.grey roofing ...