Fine-grained micas are consistent impurities in Camp-Berteaux (Morocco) and Wyoming montmorillonites. These micas give selected-area electron diffraction spot patterns with triclinic, monoclinic, and hexagonal symmetries similar to those reported previously for montmorillonites. Camp-Berteaux montmorillonite appears as folded and flexible polycrystalline aggregates with pronounced texturing along the [02], [11], and [11̅] directions. Wyoming montmorillonite displays better crystallinity and larger crystallite size, and its structure is no longer truly "turbostratic".