Black Country geology is often celebrated for those three things that were so crucial to the industrial revolution: Coal, limestone and iron ore, but there is another rock which is often forgotten: Clay.
There were many different variations of clays, and each could be used to produce characteristic products. There is no ambiguity about the out put from “Hamblet’s Blue Brick Works” in West Bromwich, for example. But an area in the south west of the Black Country, around Stourbridge, produced one special kind of clay, fireclay, or refractory clay, which made bricks capable of withstanding the immense temperatures inside blast furnaces, glass kilns and gas fittings.
Although we think of clay as a soft, putty-like substance, it would come from the pits in a rather harder state than this, and would be left exposed to the wind and the rain for many months in a process known as “weathering”. After this it could be crushed to a powder, sieved into different grades, mixed with water, left to “temper” for a further short time, eventually being ready to mould into the required shapes. Smaller bricks would be moulded by women, with men making the larger more unwieldy items. Very large items, such as the pots in which molten glass is held, were not moulded but instead made up inch by inch, in a process not dissimilar to the way in which children are taught to make “coil pots”. Each glass-house pot would need to be dried for six months before it could be used.
Fireclays have been extracted in the area since the 1500′s, and continued for around four centuries. At it’s height, products were shipped from the factories to be used worldwide. One works, built in 1888 and still standing, was intended to act as a company advertisement and has it’s entire front elevation made from their own firebricks!
The fossil fern illustrates how serendipity can often play a large part in geology – the fireclay was typically found beneath the coal measures, and it was not uncommon for owners of coal pits to also own a brick yard. It was the ready availability of the raw materials that helped to fuel industry in the region.