How was obsidian used for edged stone tools?

Obsidian was highly valued for creating edged hand tools because of its unique physical properties. As a natural volcanic glass, obsidian exhibits a conchoidal fracture, which allows it to break into smooth, curved surfaces with extremely sharp edges.123

Because of this fracture pattern, early peoples—including Native Americans and the Aztec and ancient Greek civilizations—were able to fashion the sharpest stone artifacts from the material. Like flint, which is also a brittle material that lacks cleavage planes, obsidian could be chipped to detach flakes, resulting in a keen cutting edge. These sharp edges made obsidian ideal for a variety of implements, including weapons and specialized tools. While flint was more widely distributed and served as the primary material for most edged rock tools, obsidian was utilized in a similar fashion whenever it was available.123