Some interesting stuff: Surface analysis of corroded silver coins from the wreck of the San Pedro De Alcantara (1786) Abstract A detailed morphological study of the corroded surfaces of seven silver "Pieces of Eight" recovered from the San Pedro de Alcantara shipwreck site was conducted using low pressure scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) analysis. Mosaics of the backscattered images of the coin faces indicated that the coins consist of a solid solution of -phase grains with -phase inclusion and that bromian chlorargyrite is the main corrosion product. Thin surface films of hydrated iron oxides facilitated the formation of sulphide minerals on buried coins. Surfaces were heavily abraded by the harsh erosion corrosion conditions and most bear evidence of damage from impact of other artefacts on-site. Correlations exist between the surface analyses and the data from the in-situ corrosion measurements. http://www.nma.gov.au/__data/assets/pdf_file/0020/346043/NMA_metals_s2_p02_surface_analysis.pdf
