@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix mi: <https://taxonomy.materialinstruments.com/ns#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<https://taxonomy.materialinstruments.com/id/material/obsidian>
  a skos:Concept ;
  skos:inScheme <https://taxonomy.materialinstruments.com/id/axis/material> ;
  skos:prefLabel "Obsidian"@en ;
  skos:definition "Naturally occurring dense volcanic glass, usually rhyolitic and typically but not necessarily black."@en ;
  skos:broader <https://taxonomy.materialinstruments.com/id/material/mineral> ;
  skos:closeMatch <http://www.wikidata.org/entity/Q53754> ;
  mi:searchedWithout [ dcterms:date "2026-10-21" ; mi:query "Obsidian" ; mi:scheme "uniclass" ; mi:via "https://uniclass.thenbs.com/search?query=Obsidian&filter=status%3ACurrent" ] ;
  mi:sourceBasis "referenced" ;
  dcterms:source "https://www.usgs.gov/glossary/volcano-hazards-program-glossary" ;
  dcterms:date "2026-08-30" ;
  mi:status "active" .