Assertion: calcite's cleavage | /r/HasProperty | perfect
Facets:
Source sentences:
text: The cleavage of calcite is so perfect that crystals when shattered by a hammer blow usually break into perfect little rhombohedrons.
text: Calcite has a perfect cleavage, meaning it breaks perfectly along one of its plains.
text: It has a perfect cleavage on {1011} and exhibits a trigonal crystal system.