crozzle

Crozzles, burrs and clinkers are bricks which have partly lost their shape through overheating.

The furnace was again entered, and the crust to the chests broken down; it had partially vitrified and had absorbed iron oxide and was removed in black, craggy pieces, often referred to as 'crozzle' - still sometimes to be found as a capping to walls in the vicinity of the old furnaces.

Between the ammonoid bands are three horizons of highly sheared mudstone resembling the 'crozzle' beds described by Cope (1946) at a similar stratigraphical level west of Buxton, and known also in Lancashire.