In fact some properties- especially in listed buildings it may be a building requirement that slates be used and not tiles.
The 3 main types of slate are natural, artificial and man made slates.
Natural slates are taken from natural environments such as quarries and installed on roofs to create arguably the most beautiful finish. Artificial slates are made from fibre and cement and are a lower cost alternative to natural slate. Man made slates are made by a combination of ground down slate and resin formed into a new slate. Man made slates are also much cheaper than natural slates.
Slates popularity as a roof covering and lasting prominence in the market is due to many reasons.