@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/crystal>
  a skos:Concept ;
  skos:inScheme <https://taxonomy.materialinstruments.com/id/axis/material> ;
  skos:prefLabel "Crystal"@en ;
  skos:definition "Glass with at least 10 percent by mass of lead, barium, zinc or potassium oxide, singly or together, and a refractive index of at least 1.520, with lead crystal at or above 24 percent lead oxide, as Directive 69/493/EEC classes it."@en ;
  skos:altLabel "crystal glass"@en ;
  skos:altLabel "lead crystal"@en ;
  skos:broader <https://taxonomy.materialinstruments.com/id/material/glass> ;
  skos:narrowMatch <http://www.wikidata.org/entity/Q359572> ;
  skos:notation "Ma_40_35_46_19"^^<https://taxonomy.materialinstruments.com/ns/uniclass> ;
  mi:sourceBasis "referenced" ;
  dcterms:source "composition dictionary in a materials-retrieval system (src-05); Council Directive 69/493/EEC, https://www.legislation.gov.uk/eudr/1969/493/annexes/data.xht" ;
  dcterms:date "2026-09-22" ;
  mi:status "active" .