Back up to: The Essay
5/5 Poet Fiona Hamilton contrasts clay's different states, before and after it's baked hard.
4/5 Archaeologist Rose Ferraby gets to grips with gypsum, the key mineral in plaster.
3/5 Esther Woolfson contrasts Aberdeen, the 'Granite City', with its oil and gas industry.
2/5 The writer Sara Maitland conjures with Lewisian gneiss, two-thirds the age of the earth.
1/5 Alan Garner sparks with flint, the stone that has enabled human civilisation.