The roasting must be even, and the grinding process must be finely calibrated so that the resulting coffee allows smooth passage of the hot water that extracts the flavour.

ECONOMIST: Espresso coffee

There is also little sign of preserved seeds and nuts, or of the specialised grinding stones that would have been needed to process them.

ECONOMIST: Palaeoeconomics

Some people have looked at the idea of grinding up peridotite and using it to soak up emissions from power stations, but the process turns out to be expensive, partly because of the costs of transporting all the rock.

ECONOMIST: Greenhouse gases