Sunday Stone: recording England's coal mining past
No bigger than a smartphone, this remarkable rock has layers that tell the story of the working lives and hardships of miners in the 1800s.
It formed in a water trough at the bottom of a Tyneside coal mine in North East England.
As coal miners were busy labouring to supply Britain's rapidly expanding industry, their weekly routine was being recorded in stone.
How did Sunday Stone form?
Sunday Stone is a calcareous deposit that formed as slowly flowing water deposited a white mineral (calcium carbonate) coating the drainage trough at the bottom of the mine.
When coal was extracted, the layers of carbonate laid down were blackened by the coal dust that filled the air in the mine during the working day.
What can it tell us about the working lives of miners?
The regular black-and-white striped pattern in Sunday Stone is a material record of the bleak working conditions experienced by coal miners in the nineteenth century.
A pair of light and dark bands represents one 24-hour working day. The dark band marks each day shift in the heavy, dust-laden atmosphere, whereas the thinner, light band shows the hours of inactivity during the night.
Thicker, light-coloured bands appeared on Sundays, on holidays and at other interruptions in the mine when the water would run clean for 48 hours.
In these banded patterns you can see the ongoing struggle to improve mine safety and ventilation.