The detection of toxic metals including mercury and lead has become a vital analytical tool for environmental remediation and regulation of food stocks. A prevalent obstacle with the current assessment of metal ion contamination originates from the lack of adequate assay throughput. In this context, a critical concern with current analyses stems from the fact that the majority of these assays are solution-based, and thus the response is highly dependent upon the assay environment. Herein, we describe a fluorescent dye-doped crystalline assay that offers convincing metal selection and provides detection comparable to conventional solution-based ligands used for the spectrofluorometric analysis of thiophilic heavy metal ions. While comparable in analytical performance to known methodologies, the formation of crystalline analytes provides for signal amplification and, consequently, a powerful platform whose analysis is directly amenable to high-throughput video capture systems. This procedure has been tested in a variety of scenarios and shows good performance using readily available equipment, including a commercially available Universal Serial Bus (USB) CCD camera. Furthermore, when developed in a microcapillary format, this assay is capable of screening thousands of samples per day for the presence of subnanomolar concentrations of Hg2+ using a conventional fluorescence microscope.