What is a crystal face?
crystal face One of the relatively flat surfaces by which a crystal is bounded. Faces are produced naturally during the process of crystal growth. Cut and polished gemstones are bounded by plane faces which are often produced artificially and which, therefore, are not crystal faces.
What is a cleavage plane?
Cleavage is the tendency of a mineral to break along smooth planes parallel to zones of weak bonding. Fracture is the tendency of a mineral to break along curved surfaces without a definite shape. These minerals do not have planes of weakness and break irregularly.
Do crystals have cleavage?
All cleavage must parallel a possible crystal face. This means that the crystal could have a crystal face parallel to its cleavage, but these faces are not always formed. All cleavage planes of a mineral must match that mineral's symmetry. And finally, the same mineral will always, always have the same cleavage.