So called "slates," being merely thin slabs of stone which splits into thin layers along the planes of bedding, are found in various parts of the country, and used for roofing purposes. They are tilestones rather than true slates.

Among others may be mentioned the Collywiston and Stones-field "slates," found in several quarries of the oolitic limestone formation, near Stamford in Northamptonshire, and Stow-on-the-Wold in Somersetshire.

They are good non-conductors of heat, so that they keep a house cool in summer and warm in winter; but they are very heavy, especially when soaked with wet, and therefore require roofs of heavy scantlings to support them.