Can anyone tell me where there may be bricks on site with particular collieries/mine names, or brickworks associated with them?
C19 and C20 colliery owners whose mines worked seams which had good quality underclays beneath them frequently built brickworks to exploit the clays, usually making firebricks.
In the C20 crushing machinery became cheaper and more reliable and some colliery companies crushed waste shale (instead of just tipping it as waste) to make the raw material for bricks.
It was normal practice from the later C19 to the later C20 to stamp bricks with the name of the brickworks owner or the name of the brickworks, to identify the manufacturer for, essentially, advertising purposes. Hence if the brickworks was owned by a colliery company or was located at a brickworks, the words 'XXXXXX Colliery Co Ltd' or 'XXXX Colliery' are often found on bricks.
In the mid C20 some slate quarrying companies experimented with crushing slate waste to manufacture bricks. Whilst the bricks were generlaly of good quality, the costs of crushing, of bringing coal long distances into the slate quarrying areas, and the costs (but not quite always) made the ventures uneconomic.
Bricks made from underclays are often yellow; bricks made from colliery shales are usually red (and often rough-textured due to impurities); bricks made from slate waste are usually red.