Obsidian is a type of naturally-occurring glass formed as an extrusive igneous rock. It is produced when felsic lava erupted from a volcano, cools rapidly through the glass transition temperature and freezes without sufficient time for Crystal growth. Because of the lack of Crystal structure, Obsidian blade edges can reach almost molecular thinness, leading to its ancient use of projectile points (arrow heads), and its modern use as surgical scalpel blades.
Mahogany-Obsidian is a volcanic rock that’s silica-rich and contains undulating parts of oxidized Hematite or Magnetite, which are usually colored mahogany brown or brick red within a black-colored base material. Mahogany-Obsidian can be found in places where volcanic activities have occurred.