slate

Shale lowly metamorphosed by stress and moderate temperature; tough, fine-grained and capable of being split into thin plates at an angle not related to the bedding plane. Used as roofing slates and for decoration of buildings etc.

[img_assist|nid=14660|title=|desc=Delabole Fine Rub Slate|link=none|align=left|width=224|height=200]