1) Natural material
Found on
https://www.crosswordclues.com/clue/knapping
Knapping is the shaping of flint, chert, obsidian or other conchoidal fracturing stone through the process of lithic reduction to manufacture stone tools, strikers for flintlock firearms, or to produce flat-faced stones for building or facing walls, and flushwork decoration. The original Germanic term `knopp` meant strike, shape, or work, so it .....
Found on
http://en.wikipedia.org/wiki/Knapping
• (p. pr. & vb. n.) of Knap
Found on
http://thinkexist.com/dictionary/meaning/knapping/
Knapping is the making of flint tools. Flints could be struck against each other to knock flakes away. The flint core would then said to be knapped. Sometimes small wooden or bone tools were used instead - such flint would then be pressure-flaked. It is often possible to tell if flint tools have been made at a site, as knapping will leave the small...
Found on
http://www.encyclo.co.uk/local/20766
No exact match found.
