Definition of orthoquartzite in English:

orthoquartzite

Pronunciation /ˌɔːθə(ʊ)ˈkwɔːtsʌɪt/

noun

Geology
  • (Originally) a quartzite formed from sandstone by infiltration and pressure; (now) an unmetamorphosed sedimentary rock consisting of quartz grains cemented with silica.

Origin

1920s.