ˌmäntməˈriləˌnīt noun
( -s )
Etymology: French, from Montmorillon, Dept. Vienne, France + French -ite
: a soft clay mineral RMgAl 5 Si 12 O 30 (OH) 6 . n H 2 O with R representing exchangeable bases that is usually white, grayish, pale red, or blue and that consists of a hydrous aluminum silicate with considerable capacity for exchanging part of the aluminum for magnesium, alkalies, and other bases — compare hectorite
• mont·mo·ril·lon·it·ic | ̷ ̷ ̷ ̷| ̷ ̷ ̷ ̷|nid.ik adjective