Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. rock (inorganic material)
8. igneous rock
9. [igneous rock by origin]
10. extrusive rock
11. pyroclastic rock
12. volcanic glass

Narrower term/s

• marekanite

Anotations

Scope note:

A dark, shiny glass formed in nature by the rapid cooling of lava. Obsidian is widely distributed and has been used since Paleolithic (before 3500 BCE) times for mirrors, weapons, tools, and jewelry. Obsidian is often black in color but may also be red, brown or green. It produces conchoidal fractures when cleaved. Sources of obsidian include Anatolia, Armenia, Ethiopia, Greece (Milos), Italy (Lipari, Eolie), Iceland, the U.S. (Wyoming), Mexico (Teotihuacan), Guatemala (Tikal), and Peru. Obsidian changes into pumice when it is melted.