SLATE

UF Longford Rustic Slate
Rag Slate
Riven Slate
Swithland Slate
SN Collective term for a hard, fine grained, dark coloured metamorphic rock, which splits easily; hence its common use as a roofing and flooring material, and a functional description for any rectangular, sheet, roofing material.
CL STONE
NT KILLAS
LAKE DISTRICT SLATE
SCOTTISH SLATE
WELSH SLATE
WEST COUNTRY SLATE
RT FOREST STONE (LEICESTERSHIRE)
SHALE