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 cardiac surgery. This is because well-crafted obsidian blades have a cutting edge about 3 nanometres wide, making them much sharper than steel surgical scalpels.