“It would be better for you if a millstone were hung around your neck and you were thrown into the sea than for you to cause one of these little ones to stumble.” – Luke 17:2

Basalt rock was commonly used for making millstones. A conical shaped stone was used as the base. A hollowed out stone was fitted on top with places to attach handles. Grain was poured into the top and would be ground against the stones. The ground flour would seep out of the sides.