Definition of sillimanite in English:



mass 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.’
    • ‘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.’


Mid 19th century from the name of Benjamin Silliman (1779–1864), American chemist + -ite.