Obsidian

Hardness of 5 to 5.5 on the Mohs scale, typically jet-black in color with a vitreous luster. It exhibits distinct conchoidal fracture and lacks a crystalline structure.

Formed as an extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth. Found globally in areas with recent volcanic activity.

Historically used for making sharp arrowheads, cutting tools, and spear points. Commonly utilized today in jewelry, decorative carvings, and specialized surgical scalpel blades.

Despite being primarily composed of silica, obsidian is technically a mineraloid rather than a true mineral because it lacks a crystalline lattice. Its razor-sharp edges can be finer than steel blades.

Easily identified in the field by its glass-like appearance, smooth curved fracture surfaces, and deep black coloration. Found near ancient volcanic lava flows.