a white, silvery, or green micaceous mineral that consists of hydrated aluminium silicate in monoclinic crystalline form and occurs in metamorphic rocks. Formula: Al2Si4O10(OH)2
pyrophyllite in American English
(ˌpaɪrəˈfɪlˌaɪt)
noun
a very soft, greasy, monoclinic mineral, AlSi2O5(OH), that is similar to talc in structure, used as a lubricant and in making rubber, soap, etc.; hydrous aluminum silicate