Glossary

property that causes minerals to break along well-defined planes.

Cleavage is described in terms of how easy the cleavage is produced. From easiest to hardest to produce the terms are:

• perfect
• good
• poor
• none

Many minerals exhibit cleavage only on one side, and some may exhibit different quality cleavage on different sides. We may expect to find the following criteria when analysing the cleavage of any particular mineral:

• One Direction (single cleavage)
• Two Directions
• Three Directions
• All Directions
  

Perfect, single cleavage. Diallage (1P)