Knapping an Obsidian Blade — Pressure-Flaked Volcanic Glass

Obsidian is volcanic glass formed when silica-rich lava cools so rapidly that crystals cannot form. The result is an amorphous solid that fractures with perfect conchoidal breakage, producing edges sharper than any surgical steel — measured at 30 to 50 angstroms, roughly 500 times thinner than a steel scalpel blade. Obsidian blademaking reached its peak in Mesoamerica and Anatolia between 7000 BCE and 1500 CE, where prismatic blade cores were systematically reduced to produce dozens of identical blades from a single prepared core. This blueprint teaches the simpler direct percussion and pressure-flaking technique used across the prehistoric world to produce a single utility blade suitable for cutting, scraping, and precision work. The process demands more finesse than flint knapping because obsidian is simultaneously harder and more brittle — it fractures beautifully but shatters if struck too hard or at the wrong angle.