Hélio, alumínio, manganês, ferro, cobalto, cobre, molibdênio, cério, tungstênio, ouro, rádio, tório e urânio em Mumford (1934)

There is still another important consequence of this new complex. While certain products of the neotechnic phase, like glass, copper, and aluminum, exist like iron in great quantities, there are other important materials – asbestos, mica, cobalt, radium, uranium, thorium, helium, cerium, molybdenum, tungsten – which are exceedingly rare, or which are strictly limited in their distribution. Mica, for example, has unique properties that make it indispensable in the electrical industry: its regular cleavage, great flexibility, elasticity, transparency, non-conductivity of heat and electricity and general resistance to decomposition make it the best possible material for radio condensers, magnetos, spark plugs, and other necessary instruments: but while it has a fairly wide distribution there are important parts of the earth that are completely without it. Manganese, one of the most important alloys for hard steel, is concentrated chiefly in India, Russia, Brazil and the Gold Coast of Africa. With tungsten, seventy per cent of the supply comes from South America and 9.3 per cent from the United States; as for chromite, almost half the present supply comes from South Rhodesia, 12.6 per cent from New Caledonia, and 10.2 per cent from India. The rubber supply, similarly, is still limited to certain tropical or sub-tropical areas, notably Brazil and the Malayan archipelago. (Mumford 1934:232)

MUMFORD, Lewis. 1934. Technique and civilization. New York: Harcourt, Brace and Company.