Talc crystal morphology

The size of an individual talc platelet (= a few thousand elementary sheets) can vary from approximately 1 micron to over 100 microns depending on the deposit. It is this individual platelet size that determines a talc's lamellarity. A highly lamellar talc has large individual platelets whereas a compact (known as microcrystalline) talc's platelets are much smaller.

Macro-crystalline talc	Micro-crystalline talc

The elementary sheets are stacked on top of one another, like flaky pastry, and because the binding forces (known as Van der Waal's forces) linking one elementary sheet to its neighbors are very weak, the platelets slide apart at the slightest touch, giving talc its characteristic softness.