100pts: Why was obsidian used to make scalpels?

Research also confirms that incisions carried out with obsidian produce narrower scars and fewer inflammatory cells. This is because on cellular level, obsidian knife cuts between cells rather than tearing it in case of a steel knife, hence, a sharper cut allows the wound to heal more easily with negligible scarring.

Answer: Obsidian has been used as a cutting tool since the Stone Age, but modern versions of obsidian scalpels are manufactured by a Virginia archaeologist using a pressure flaking process. Each knife can be used from 10 to 20 times before being discarded, Green says. He keeps his blades in a cold sterilizing solution to preserve their sharpness.