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

Narrower term/s

• trass
• tuff[+]
  • peperino [+]
    • sperone
  • santorin
  • Neapolitan yellow tuff
• volcanic glass[+]
  • pumice (volcanic rock) [+]
    • tezontle
  • obsidian [+]
    • marekanite
  • perlite
  • tachylite
  • pumice (pigment) [NP]

Anotations

Scope note:

Rock formed when dislocated and rupturing solid material is explosively or aerially ejected from a volcanic vent or rock formed when solid fragments are incorporated into moving lava.