Frosterley marble.
Trying to identify that black limestone with the fossil coral in it has been bugging me for a year. Went into the Laing art galley in Newcastle the other day and they have a polished block of it on display on the ground floor and tiles made from it in the floor itself. " Frosterley marble" it is. From Durham.
http://www.topografik.co.uk/laing-fossil/
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