This stage will consist of microbiological assaying of the archaeological, geological, and composite samples. Microorganism susceptibility assays will determine the bioactivity of minerals against reference bacterial strains (e.g. Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, and Escherichia coli). Assays will include the determination of minimum inhibitory concentration of minerals (MIC; lowest concentration that inhibits bacterial growth) and minimum bactericidal concentration (MBC; lowest concentration that kills bacteria).