noun

• A fine-grained volcanic igneous rock composed of alkali feldspars and nepheline.

  ‘South of the city of Isparta pyroclastic rocks are interbedded with rhyolite, trachyte, phonolite and lamproite flows (the Golcuk and Bucak Volcanics of Savascin et al.).’

  More example sentences

  • ‘In the Canaries, the lavas are much more compositionally varied in each of these stages, ranging from tholeiitic basalts to phonolites and trachytes.’
  • ‘The dominant magma types are basalts and hawaiites, with lesser amounts of trachytes, quartz trachytes, alkali rhyolites and phonolites.’
  • ‘Plagioclase dramatically removes Sr at intermediate stages and alkali feldspars sequester Ba and Rb as late-stage trachytes and phonolites form in alkaline magmas.’