Sheet silicates exhibit one directional cleavage.  This is because the bonding between the sheets is weak.  These minerals have a greasy feel and lubicating qualities.  An example of weak bonding is mica,in which the sheets separate easily.

 The kaolinite group includes kaolinite and three others with similar chemical composition but different structure.  The other three are dickite (funny name) , nacrite, and halloysite.  Kaolinite is important for use in pharmaceuticals, firebrick, china, and as a whitening agent.

I joined an online wire wrap group today.  I wonder if I will learn anything.