[pahy-ruh-fil-ahyt, pahy-rof-uh-lahyt]
  1. Mineralogy. a phyllosilicate, AlSi2O5(OH), usually having a white or greenish color, and occurring in either foliated or compact masses, the latter variety being used like soapstone.

Origin of pyrophyllite

First recorded in 1820–30, pyrophyllite is from the German word Pyrophyllit; so called because it exfoliates when heated. See pyro-, -phyll, -ite1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for pyrophyllite

Historical Examples of pyrophyllite

  • Pyrophyllite (hydrated aluminum silicate) resembles talc in some of its properties and is used in much the same way.

British Dictionary definitions for pyrophyllite


  1. a white, silvery, or green micaceous mineral that consists of hydrated aluminium silicate in monoclinic crystalline form and occurs in metamorphic rocks. Formula: Al 2 Si 4 O 10 (OH) 2
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012