MINERALS 249 



simply this. The ores used to produce copper have grown leaner 

 and leaner and necessity has forced engineers to make the best 

 of what is left. 



Copper is just an example of technical advances that have 

 been made in the manufacture of most minerals. When Sie- 

 mans, for example, invented the open hearth process for mak 

 ing steel, he in effect increased the world's iron reserve by 

 many millions of tons. The reason for this was that his process 

 permitted the use of scrap steel and scrap iron as well as pig 

 iron in making steel. This meant that iron which had been used 

 before could now be melted up many times and used for new 

 products, thus taking the place of newly mined iron ore. Today, 

 about one-third of the steel products used are made from re 

 covered scrap. 28 



In the case of copper, the use of scrap metal is even more 

 advanced. Copper is not so quickly destroyed by corrosion as 

 steel. In addition to this, copper is rarely used in such a way 

 that it is destroyed. Thus today about 64 per cent of the copper 

 used comes from scrap. 



Improvement in the use of a mineral also saves great quan 

 tities of it. For instance, if steel and iron could be prevented 

 by a cheap process from rusting, millions of tons could be saved 

 every year. And a rust proof steel would not only save mil 

 lions of tons of steel; it would also save many tons of lead, 

 zinc, and tin which are used as coverings to prevent rust on iron 

 and steel. When, for instance, the coating of fence wire finally 

 breaks through, the iron or steel rusts, and the whole is dis 

 carded. It is lost forever so far as man is concerned. 



The use of coal to produce electric power is a good example 

 of just how much can be saved by advanced methods of min 

 eral use. In 1919 it took 3.2 pounds of coal to produce 1 kilo- 



28 Erich W. Zimmermann, World Resources and Industries, New York, Harper 

 tf Brothers, 1933, p. 600. 



