Obsidian has been used in cardiac surgery, as well-crafted obsidian blades have a cutting edge many times sharper than high-quality steel surgical scalpels, with the edge of the blade being only about 3 nanometres wide.
Obsidian has been used in heart surgery, as well-built obsidian blades have an edge much sharper than steel surgical knives, with the edge of the blade being only about 3 nanometres wide.