Silver is one of the more noble metals.
Highly malleable, it is worked in ornaments or found in coins, bullion, or such decorative utilitarian items as candle stick holders. An oddity among the noble heavier metals silver is non-toxic and its corrosion residue does not form an electrically passive surface layer when submerged in a marine environment. This is an indication that silver may be free to corrode and in fact, is not always found in good condition on a wreck site in salt water. Silver invariably contains a high percentage of copper which may help partially passivate the concretion which encapsulates it. In anaerobic concretions the original surface or the layer which contains the archaeological surface is a black or dark grey silver chloride layer imbedded in the concretion.