noun

• An aluminosilicate mineral typically occurring as fibrous masses, commonly in schist or gneiss.

  ‘Muscovite and aluminosilicates are almost entirely absent although, where present, the aluminosilicate is sillimanite.’

  More example sentences

  • ‘The aluminium silicate minerals andalusite, kyanite, and sillimanite are good examples of this phenomenon of polymorphism.’
  • ‘Growth of titanite took place during the metamorphic climax in rocks from the kyanite and sillimanite zones.’
  • ‘Kyanite and sillimanite may also be present but only as minor components.’
  • ‘The country rock was regionally metamorphosed to above the sillimanite isograde.’