page_title: Phonolite
section_title: Mineralogy and petrology
hierarchical_section_title: Phonolite / Mineralogy and petrology
caption_attribution_description: English: Dyke in Tsili
context_page_description: Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic to porphyritic. Its intrusive equivalent is nepheline syenite.
  The name phonolite comes from the Ancient Greek meaning "sounding stone" because of the metallic sound it produces if an unfractured plate is hit; hence the English name clinkstone.
context_section_description: Phonolite is a fine-grained equivalent of nepheline syenite. They are products of partial melting, are silica-undersaturated, and have feldspathoids in their normative mineralogy.
  Mineral assemblages in phonolite occurrences are usually abundant feldspathoids (nepheline, sodalite, hauyne, leucite and analcite) and alkali feldspar (sanidine, anorthoclase or orthoclase), and rare sodic plagioclase. Biotite, sodium-rich amphiboles and pyroxenes along with iron-rich olivine are common minor minerals. Accessory phases include titanite, apatite, corundum, zircon, magnetite and ilmenite.
  Blairmorite is an analcite-rich variety of phonolite.
caption: Phonolite dike in Tsili in Ethiopia
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