Copper objects

The green coating on copper objects such as the Statue of Liberty is a mixture of copper salts,... 

Three copper objects from the Tunacunnhee site with pseudomorphs after fabric adhering to their surfaces were selected for analysis. These were the copper plate, one set of earspools from Mound C (F-30), and a copper earspool from Mound E (F-33). 

Byers (19) reports analyses of Etowah fabrics that adhered to copper objects from Mound C. One was described initially by Willoughby (23) in 1932, and one was described by Moorehead (24) in the same year. Schematic illustrations of both fabrics bear a resemblance to fabric bundle No. 840, but differences also are seen. In the first of these fabrics, Byers indicates a spaced fabric with a System A (warp) as a single, two-ply, S-twist yarn and a System B (weft) as two, two-ply, S-twist yarns twining around the System A yarns. He notes that no selvage was present and that in certain areas Z-twist warp was used and provided a ribbed effect. Since his examination, the plate to which the fabric was attached has been cleaned. 

The identification of fiber preserved as pseudomorphs on prehistoric Amerindian copper objects proved more difficult. Yarn pseudomorphs composed of mineralized fiber bundles typical of some sort of bast fiber were observed, but identification beyond this gross generic classification was not possible (3). The details of construction of twined fabric pseudomorphs also are not well known because the pseudomorphs cannot be turned over for study of the reverse side. Similarly, the particular feather type of feather pseudomorphs cannot, as yet, be classified. 

Electroplating is the process of depositing dissolved metal cations in a smooth even coat onto an object used as an active electrode. Electroplating is used to protect metal surfaces or for decoration. For example, to electroplate a copper surface with nickel, a nickel rod is used for the anode and the copper object is used for the cathode. NiCl2(ag) or another substance with free nickel ions is used in the electrolytic cell. Ni(s) Np (ag) i 2e" occurs at the anode and NP (ag) + 2e —>Ni(s) occurs at the cathode. 

Did you know that the Statue of Liberty is made of copper sheets attached to a steel skeleton Why does it appear green rather than the reddish-brown color of copper When copper is exposed to humid air that contains sulfur compounds, it undergoes a slow oxidation process. Under these conditions, the copper metal atoms each lose two electrons to produce Cu ions, which form the compounds CuS04 3Cu(0H)2 and Cu2(0H)2C03. These compounds are responsible for the green coat or patina found on the surface of copper objects that have been exposed to air for long periods of time. Figure 16.11. 

Finally, it should be mentioned that, in the past, the antiquary has not always possessed the requisite chemical or metallurgical knowledge, with the result that relics have not infrequently been most incorrectly described. Copper objects have been classed as bronzes and vice versa, whilst, to the present author s own knowledge, haematite arrow-heads have been described as made of iron of such excellent quality that it had resisted corrosion throughout the ages ... 

Producing verdigris artificially on a copper object isn t an easy task. Artists usually resort to using acrylic paints to mimic the natural reaction of copper with acidic compounds in the air. By the way, the patina on copper roofs is a mixture of copper carbonate and copper sulfate. 

Lead is extremely rare in the metallic state. Consequently, the appearance of lead metal in archaeolc cal finds provides evidence that man had learnt to extract lead from its ore. Exca tions in Central Anatolia have unearthed small beads of metallic lead, alongside gold and copper objects. These have been dated to at least 7000-6500 BC, if not a great deal earlier. This would point to lead having been the first metal to be smelted. Although copper may have been melted and worked by about 4300 BC, it was not until some 700 years later that copper was smelted from its ore." ... 

Glover RD, Miller JM, Hutchison JE (2011) Generation of metal nanoparticles from silver and copper objects nanoparticle d3mamics on surfaces and potentials sources of nanoparticles in... 

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