Native metal

Few metals occur in the earth s crust uncombined with others. Those that do, such as gold, silver, mercury, and some copper, are known as the native metals. Together with some native nonmetals such as carbon and sulfur, the native metals make up the relatively small group of native elements, naf-urally occurring masses of single elements that were recognized and put to use by humans in quite early times. Most metals occur in nature combined with nonmetals in the form of mineral and rock deposits, and from fhose minerals they are extracted by means of a variety of metallurgical fechniques. 

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Pure iron is a silvery white, relatively soft metal and is rarely used commercially. Typical properties are Hsted in Table 1. Electrolytic (99.9% pure) iron is used for magnetic cores (2) (see Magnetic materials, bulk). Native metallic iron is rarely found in nature because iron which commonly exhibits valences of +2 and +3 combines readily with oxygen and sulfur. Iron oxides are the most prevalent form of iron (see Iron compounds). Generally, these iron oxides (iron ores) are reduced to iron and melted in a blast furnace. The hot metal (pig iron) from the blast furnace is refined in steelmaking furnaces to make steel... 

The monetary use of silver may well be as old as that of gold but the abundance of the native metal was probably far less, so that comparable supplies were not available until a method of winning the metal from its ores had been discovered. It appears, however, that by perhaps 3000 BC a form of cupellation was in operation in Asia Minor and its use gradually... 

The reddish metal was already known in prehistoric times. It occasionally occurs as a native metal, but mostly in conspicuous green ores, from which it is extracted relatively easily. It is convenient to work, but not very hard. Not very optimal as a tool ("Otzi the Iceman" had a copper axe with him). Only through the addition of tin is the more useful bronze obtained. Its zinc alloy is the versatile and widely used brass. Copper is one of the coinage metals. Water pipes are commonly made of copper. Its very good thermal and electrical conductivity is commonly exploited (cable ), as well as its durability (roofs, gutters), as the verdigris (basic copper carbonate) protects the metal. Cu phthalocyanines are the most beautiful blue pigments. Seems to be essential to all life as a trace element. In some molluscs, Cu replaces Fe in the heme complex. A 70-kg human contains 72 mg. 

Native elements Single element Native metals, native nonmetals... 

Iron does not occur in nature as a native metal. Lumps of meteoritic iron, which fell to the surface of the earth from outer space, are often found, however. It has been argued whether the earliest iron used by humans was of meteoritic origin or smelted from ores (Piaskowsky 1988). Combined with other elements, iron occurs in a varied range of ferruginous (iron-containing) ores that are widely dispersed on the upper crust of the earth some common iron ores often used for smelting are listed in Table 37. 

Lead (chemical symbol Pb, from the Latin name for the metal, plumbum) is a gray, soft, ductile, and very poisonous metal, although its poisonous properties were probably unknown to the ancients. The metal has been used, particularly in China and India, since very ancient times. Lead is not found in nature in the native, metallic form, although tiny particles of the metal are occasionally encrusted in rocks. It is unlikely, therefore, that the metal would... 

Tin (chemical symbol Sn, from the Latin name of the metal, stannum) occurs as a native metal only as small, rare nuggets it is very doubtful, therefore, whether native tin would have been noticed, never mind used, by ancient people. Nevertheless, tin was one of the earliest metals to have been produced. Tin ores occur in few places on the upper crust of the earth, mostly as the mineral cassiterite or tin stone (composed of tin oxide) from which most tin has been and still is extracted. Tin stone is a usually brown or black,... 

There are two allotropes of antimony. The native metallic form is one allotrope, and the other allotrope is an amorphous grayish form. Antimony is a true metalloid that is brittle with a low melting point. And similar to nonmetals, it is a poor conductor of heat and electricity. 

In industrial applications of metal deposition a metal M is deposited either on the native metal substrate M or on a foreign metal substrate S. As an example of the former, Cu is electrodeposited on a Cu substrate formed by electroless Cu deposition on an activated nonconductor in the fabrication of printed circuit boards. As an example of the latter, Ni is electrodeposited on Cu in the fabrication of contact pads in the electronics industry. 

Analytical or Alloys employs FP and should be used for native metals and provides typical DL of 0.1-0.5%. 

Filiform Having the shape of a thread or filiment, roughly 10 microns or less in thickness (=fine-fibrous). The term is often applied to wirelike growths of native metals. 

A. Lucas stated that antimony and its compounds were rarely used in ancient Egypt. He mentioned one example of a Nineteenth-Dynasty eye paint consisting of antimony sulfide the use in the same Dynasty of antimony and lead to color glass yellow some small beads of metallic antimony, probably made from native metal in the Twenty-second Dynasty (945-745 B.C.) a tablet of metallic antimony which M. Julius... 

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