The majority of scientists hold the opinion that mankind first knew metal in the form of native copper. In particular, at this period the malleability of native copper was realized, and its brittleness when cold worked, as well as the need of annealing to cold forge the necessary tools. The melting of copper was discovered later when native copper was met with in association with ores.
These opinions are shared by H. H. Coghlan and H. Otto and W. Witter, though the first mentioned also pointed out that in some regions artifacts made from copper alloys existed in early periods while artifacts made of pure copper might be met with in the latest periods.
V. I. Vernadski also had some doubt about the unconditional validity of this theory. However, he did not deny that where native copper was distributed it was the first metal replacing (although only partly) stone and bone for making tools. In certain cases such an assertion has been supported by old and unreliable analyses of ancient artifacts, as well as by some mistakes in the determination of their age.