Contents of Cleavage

2.1 What are the properties of minerals?

Cleavage - the way a mineral "breaks" into smaller bits of characteristic shape.

flat cleavage faces
smaller pieces resemble larger bits

The common mica minerals, silvery muscovite and nearly black biotite, have a single cleavage direction. This means that a knife blade or fingernail easily separates samples into thin, transparent sheets

Calcite breaks into regularly shaped pieces that have six planar sides with rhomb shapes. The planes defining the pieces are cleavage planes and the pieces of calcite are cleavage fragments

Fig 2.5b

Fig 2.6