Medium hardness: a volcanic ignimbrite closely resembling sandstone in texture. Containing 95% silica with random light brown veining.
Portuguese Limestone
Colouration: Off white with light fleck.
A fine grained medium hard limestone.
Bluestone
Colouration: Dark grey - Anthracite
A hard wearing igneous material suited for hearths and reveal/opening slips, recommended for wood burning fires where marking of the hearth is not desirable.