həˈlȯiˌsīt, haˈ-, -ˌzīt noun
( -s )
Etymology: French, from Omalius d' Halloy died 1875 Belg. geologist + French -ite
: a clay mineral Al 2 Si 2 O 5 (OH) 4 . n H 2 O occurring in soft white or light-colored masses and in at least two states of hydration n .2, n .4