Much depends on the style of the fireplace and how strong a visual look you wish it to have. The most common materials to use are Honed Black Slate, Honed Black Granite or Honed Limestone
Honed Black Slate gives a matt black consistent appearance to any fireplace. This stone was traditionally used in the slate producing parts of the UK (Scotland, Wales, the Lake District and Cornwall) . It also tended to be used in conjunction with white marble in formal Victorian fireplaces and therefore is also likely to appear in large urban grand Victorian villas and properties of this nature. It is a durable material but can be prone to scratching if things are dragged across the surface.
Honed Black Granite has been used in recent times as a more durable alternative to slate. It is hard and easy to look after. It is also very difficult to scratch. However it has a slightly higher sheen and therefore if you are looking for a matt traditional black hearth it is wiser to stick with slate. It tends to be most common with white marble Victorian style fireplaces
Honed limestone is the most traditional material to use with more rustic fireplaces. This can vary from the soft grey tones of Portland limestone to the soft sandy tones of Bath Stone or Lincoln. The advantage of a limestone hearth is the light warm colour tones. However if you are using an open wooden fire a light limestone hearth will show the dust and deposits from the fire. They are easily cleaned up with the hose from a vacuum cleaner after use.