A thin film of Au exposed to mercury vapor disrupts forming separated domains of AuHg amalgam. After evaporation of Hg at high temperature An islands are formed and the domain pattern changes. A detailed quantitative morphological analysis and comparison of two types of surface patterns before and after the evaporation of Hg is performed. We have found that during the evaporation of Hg at high temperature the islands decrease their sizes and their shapes become more circular. The domain pattern formed by the amalgam domains is found to be characterized by one length scale. After the removal of mercury the characteristic length scale vanishes and the structure function takes the shape typical for the random droplet morphologies.