Scoria brick is a type of blue-grey brick made from

slag The general term slag may be a by-product or co-product of smelting (pyrometallurgical) ores and recycled metals depending on the type of material being produced. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be c ...

, originally manufactured from the waste of the steelworks of Teesside, common across the

North-East of England The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A ''compass rose'' is primarily composed of four cardinal directions—north, east, south, and west—each ...

. The bricks were also exported around the world and can be found in Canada,

West Indies The West Indies is an island subregion of the Americas, surrounded by the Atlantic Ocean, North Atlantic Ocean and the Caribbean Sea, which comprises 13 independent island country, island countries and 19 dependent territory, dependencies in thr ...

, Netherlands, Belgium, United States, India and South America. The word ''Scoria'' originally comes from Greek, meaning "Excrement", but came to be used by the Romans for a kind of volcanic rock. The bricks were invented by Darlington industrialist Joseph Woodward, in the 1870s, with him registering a patent in 1873 and forming the "Tees Scoriae Company" the same year. At its peak the company was taking 30% of the slag from the South-Tees works. The bricks were produced by pouring the slag cauldrons, coming on trains from the steel works, into moulds made with hinged bottoms and mounted on a revolving platform allowing the moulds to be filled separately. As the bricks solidified they were removed and placed in a beehive oven, where the residual heat annealed the whole of the brick. The bricks were found to be extremely durable against water, frost, chemicals and heavy loads, which led to them being used as a road surface. On the other hand, an early trial of the bricks in Liverpool found the bricks to wear unevenly and become slippery in wet conditions.

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{{reflist Bricks Pavements