Biotite (black mica) and muscovite (white mica) are both minerals that have perfect basal cleavage--one direction. It cleaves into thin sheets. Feldspars (albite, oligoclase, andesine, labradorite,...
Cleavage is most often used with the following 3 meanings: MITOSIS: a phase during Mitosis when cells split and multiply GEOLOGY: The splitting of a complex crystal/mineral formation into a simpler...