Obsidian is a naturally occurring volcanic glass formed as an extrusive ingenious rock. When the felsic lava emerging from a volcano cools rapidly with minimum crystal growth, obsidian is produced. Obsidian is hard and brittle and fractures with very sharp edges. In the past it was employed in cutting and piercing tools as well as surgical scalpel blades.

Obsidian can be found in locations which have experienced volcanic eruptions. It can be found in Argentina, Armenia, Canada, Chile, Greece, El Salvador, Guatemala, Iceland, Italy, Japan, Kenya, Mexico, New Zealand, Peru, Scotland and the USA.

Though not approved by the Food and Drug Administration of USA for use on humans, obsidian is used by some surgeons as scalpel blades. A well-crafted obsidian blade is only 3 nanometers thick and much more sharper than high-quality steel surgical scalpels.

Even the sharpest metal scalpel has a jagged and irregular edge when viewed under a powerful microscope. But even under an electron microscope, obsidian blade is smooth and even. One study found that obsidian incisions produced narrower scars, fewer inflammatory cells, and less granulation tissue when tried on a group of rats. Obsidian scalpels may currently be purchased for surgical use on research animals.

Obsidian is used as a gemstone and for ornamental purposes. It presents different appearances according to the manner in which it is cut. Small rounded obsidian nuggets embedded within a grayish-white perlite matrix are called ‘Apache tears’.