![Sunday stone at the natural history museum](https://upload.wikimedia.org/wikipedia/commons/a/ab/Sunday_stone_at_the_natural_history_museum.JPG)
Sunday stone is an artificial stone composed of porous
barium sulfate that formed on the walls of drainage pipes of some coal mines.
[ It is striped due to differing levels of coal dust produced during the day and night shifts.] In some cases there is a broader stripe generated every seven days due to active mining not taking place on a Sunday. Broader stripes would also appear when work stopped for other reasons.[ In one case a broad stripe was found to coincide with workers being given the day off to view a ]cock fight
A cockfight is a blood sport, held in a ring called a cockpit. The history of raising fowl for fighting goes back 6,000 years. The first documented use of the ''word'' gamecock, denoting use of the cock as to a "game", a sport, pastime or ente ...
.[ Breaks of more than a day would produce an even broader stripe such as when Christmas fell on a Monday.]
The Sunday stone would over time block the drainage pipes necessitating their replacement. Where mines have improved ventilation, reducing the level of coal dust in the air, Sunday stone has ceased to be formed.
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Coal mining