from Primitive Technology:

The manufacture of a stone ax including the handle from using only primitive tools and materials. It is a celt (pronounced “selt”) a type of ax with a polished stone head wedged into a hole or mortise at the end of a wooden handle (not to be confused with a “Kelt” referring to a Celtic person). The head took about a week and a day to make as I chose to make it from a particularly large piece of basalt.