Black Obsidian

Physical Properties

Hardness: 5-5.5 | Color: Jet black | Luster: Vitreous/glassy | Structure: Amorphous (non-crystalline) | Cleavage: None/Conchoidal fracture | Specific Gravity: 2.35-2.6

Formation & Geological History

Formed by the rapid cooling of silica-rich lava, preventing the growth of crystals. Typically found in volcanic regions from various geological ages, often Pleistocene or Holocene.

Uses & Applications

Used in jewelry (beads, cabochons), surgical blades (sharper than steel), and ornamental carvings. Historically used for arrowheads and scrapers.

Geological Facts

Obsidian is technically a glass, not a mineral, because it lacks a crystalline structure. It was highly prized in the Mesoamerican and Neolithic cultures for trade and tool making.

Field Identification & Locations

Identify in the field by its jet-black color and distinct conchoidal (shell-like) fracture. Found in volcanic areas like Oregon, Mexico, Iceland, and Japan. Best identified by its extremely smooth, glassy surface.

Identified on: 5/3/2026

Mode: Standard