It seems that early man possessed the knowledge related to qualified stone shown by the way they choose particular stone as the material. The stone tools seen on various site illustrate the usage of stone material containing high silica quality like quartzite, silicified limestone, silicified tuff, chalcedony, jasper, chert, silicified andesitic, basaltic andesitic, fossil of wood, silicified coral. Those are the hard stone material possessing soft and shiny texture. Such stone will make a sharp glass-like cutting edge.
(Wahyu Widianta, Ilham Abdullah, Haris Rahmanendra, Iwan SB)
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