noun hal·loy·site \həˈlȯiˌsīt, haˈ-, -ˌzīt\

Definition of halloysite



  1. :  a clay mineral Al2Si2O5(OH)4.n H2O occurring in soft white or light-colored masses and in at least two states of hydration n =2, n =4

Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Join MWU now and get access to America’s largest dictionary, with:

  • 300,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Origin and Etymology of halloysite

French, from Omalius d'Halloy †1875 Belgian geologist + French -ite

Seen and Heard

What made you want to look up halloysite? Please tell us where you read or heard it (including the quote, if possible).


capable of being understood in two ways

Get Word of the Day daily email!