Mechanical properties of nanometer-thick multilayer vermiculite, a layered silicate, were investigated by atomic force microscopy (AFM) contact mode imaging. Membranes suspended over circular holes were with exfoliated vermiculite platelets. The elastic modulus and pre-stress of each membrane were obtained using AFM combined with finite element analysis. The exfoliated multilayer vermiculite membranes had an average in-plane elastic modulus and average pre-stress of 175 +/- 16 GPa and 55 +/- 13 MPa, respectively. (C) 2012 Elsevier B. V. All rights reserved.