The presence of clay minerals, hydrous aluminosilicates that are smaller than 2 ¿m can alter the elastic and plastic behavior of materials significantly. We have used Atomic Force Acoustic Microscopy (AFAM) to measure elastic properties of clay minerals. We demonstrate the AFAM technique for measuring elastic properties of soft materials. Using this technique, we present first-ever quantitative measurements of Young's modulus in clay. The Young's modulus of dickite was measured as 6.2 GPa.