WELSH SLATE SIZES: 40 x 40 x 1.5 - 2cm / 60 x 30 x 1.5 - 2cm / 30 x R x 1.5 - 2cm / 40 x R x 1.5 - 2cm This hard dense semi riven black Welsh slate is quarried near Ffestiniog in Wales. This traditional slate is the strongest and most durable slate that can be used for flooring. We offer this material in a variety of sizes and bespoke sizes can be produced to order.