@prefix qx8: <http://data.loterre.fr/ark:/67375/QX8> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

qx8: a skos:ConceptScheme .
qx8:-N5RTB4ND-P
  skos:definition "Le (ou la) quartzite est une roche siliceuse massive, constituée de cristaux de quartz soudés. Il présente une cassure conchoïdale. Sa couleur est généralement claire. Il existe deux types de quartzite : le quartzite métamorphique (ou métaquartzite), issu de la recristallisation d'un grès, d'une radiolarite ou d'un filon de quartz ; le quartzite sédimentaire (ou orthoquartzite), issu de la cimentation par diagenèse d'un grès. La différenciation entre ces deux types est impossible avec un seul échantillon. (Adapté de : <a href=\"https://fr.wikipedia.org/wiki/Quartzite#:~:text=Le%20(ou%20la)%20quartzite%20est,Sa%20couleur%20est%20g%C3%A9n%C3%A9ralement%20claire.&text=M%C3%A9taquartzite%20bleut%C3%A9%20de%20Solli%C3%A8res%20en,le%20massif%20de%20la%20Vanoise\">https://fr.wikipedia.org/wiki/Quartzite#:~:text=Le%20(ou%20la)%20quartzite%20est,Sa%20couleur%20est%20g%C3%A9n%C3%A9ralement%20claire.&text=M%C3%A9taquartzite%20bleut%C3%A9%20de%20Solli%C3%A8res%20en,le%20massif%20de%20la%20Vanoise</a>.)"@fr, "Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals. The term quartzite is also sometimes used for very hard but unmetamorphosed sandstones that are composed of quartz grains thoroughly cemented with additional quartz. Such sedimentary rock has come to be described as orthoquartzite to distinguish it from metamorphic quartzite, which is sometimes called metaquartzite to emphasize its metamorphic origins. Quartzite is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica content of the rock provides little material for soil; therefore, the quartzite ridges are often bare or covered only with a very thin layer of soil and little (if any) vegetation. Some quartzites contain just enough weather-susceptible nutrient-bearing minerals such as carbonates and chlorite to form a loamy, fairly fertile though shallow and stony soil. Quartzite has been used since prehistoric times for stone tools. It is presently used for decorative dimension stone, as crushed stone in highway construction, and as a source of silica for production of silicon and silicon compounds. (Adapted from: <a href=\"https://en.wikipedia.org/wiki/Quartzite\">https://en.wikipedia.org/wiki/Quartzite</a>)"@en ;
  skos:inScheme qx8: ;
  skos:exactMatch <http://data.loterre.fr/ark:/67375/26L-NHS0DF6C-0>, <https://fr.wikipedia.org/wiki/Quartzite#:~:text=Le%20(ou%20la)%20quartzite%20est,Sa%20couleur%20est%20g%C3%A9n%C3%A9ralement%20claire.&text=M%C3%A9taquartzite%20bleut%C3%A9%20de%20Solli%C3%A8res%20en,le%20massif%20de%20la%20Vanoise>, <https://en.wikipedia.org/wiki/Quartzite> ;
  skos:broader qx8:-13M320QW-Q ;
  a skos:Concept ;
  skos:prefLabel "quartzite"@fr, "quartzite"@en .

qx8:-13M320QW-Q
  skos:prefLabel "roche métamorphique"@fr, "metamorphic rock"@en ;
  a skos:Concept ;
  skos:narrower qx8:-N5RTB4ND-P .