Basalt and volcanoes
Basalt (bu-SALT) is a volcanic stone – it forms from the lava that volcanoes spew out when they erupt. So it is an igneous rock. It is a very hard, black stone.
What is basalt made of?
More about igneous rocks
All our geology articles
It makes a good stone for grinding wheat and barley and millet into flour. By the Stone Age people who lived in places in Africa and West Asia where there was basalt were already selling these grindstones to their neighbors, and even to people living pretty far away. Basalt is heavy, but people moved it around on boats, so they didn’t have to carry it themselves.
Early African ships and sailing
History of wheat
Where does barley come from?
By the beginning of the Bronze Age, stone carvers in Ancient Egypt also used basalt to make statues. When you polish it, basalt makes very dramatic looking shiny black statues.
All our ancient Egypt articles
In the Roman Empire, the Romans used this hard stone for roads, because it was very hard so it would last a long time. They still used basalt for grinding stones, too. Roman traders often shipped grinding stones on sailing ships to markets all over the Mediterranean, so people could have good grinding stones even where there weren’t any volcanoes.
Roman ships and sailing
All our ancient Rome articles
In the Roman Empire, people made more complicated basalt grindstones. This one, shaped like an hourglass set over a cone-shaped piece underneath, is a typical Roman grain mill.
Slavery in ancient Rome
Where do donkeys come from?
More about Roman food
Bibliography and further reading about igneous stone and and volcanoes:
Volcanoes, by Peter Francis and Clive Oppenheimer (second edition 2004).