Group 12 element ancient times as well as in alloys such as brass that have been found to be over 2000 years old. Zinc was distinctly recognized as a metal under the designation of "Fasada" in the medical Lexicon ascribed to the Hindu king Madanapala (of Taka dynasty) and written about the year 1374. The metal was also of use to alchemists. The name of the metal was first documented in the 16th century, and is probably derived from the German for the needle-like appearance of metallic crystals. The isolation of metallic zinc in the West may have been achieved independently by several
Copper alloys in aquaculture susceptible to chloride stress corrosion. Copper–silicon has a long history of use as screws, nuts, bolts, washers, pins, lag bolts, and staples in wooden sailing vessels in marine environments. The alloys are often composed of copper, silicon, and manganese. The inclusion of silicon strengthens the metal. As with the copper–nickel alloys, corrosion resistance of copper–silicon is due to protective films that form on the surface over a period of time. General corrosion rates of 0.025–0.050mm have been observed in quiet waters. This rate decreases towards the lower end of the range over long-term exposures (e.g., 400–600 days). There is generally