(D) The United States lacks certain minerale almost entirely. The 
United States will in the future, as in the past, depend on other 
countries almost entirely for its nickel, cobalt, platinum, tin, gem 
diamonds, black diamonds, or “carbonado.” and diamond dust 
and bort. ; 
Immort of minerals of classes © and D will continue to be necessary 
and can be stopped only at great cost, Future exploration may disclose 
adequate supplies of some of those minerals in which the United 
States is now deficient but for the most part we believe that the 
geologic conditions are sufficiently well known to make this out- 
come unlikely. With certain exceptions noted below, we believe 
that any attempt by legislation to keep foreign supplies out and to 
make domestic supplies of these minerals suffice for United States 
needs will not succreed except at excessive cost in efficiency and 
money. Such a course also would mean depletion of limited supplies 
which may seriously endanger the country in a time of critical 
future need. In the meantime, governmental restrictions on im- 
ports (probably inducing retaliatory measures abroad) are likely to 
make it more difficult for American enterprise to find and develop 
needed resources of these minerals in foreign countries where the 
geologic conditions are more favorable. 
Conditions under which import taxes on minerals of classes 0 and 
D might be desirable. As long as import channels of these minerals 
are not closed we do not oppose tariffs or other measures which 
are designed to offset differences in living costs and to aid in main- 
taining a sound nucleus for an industry which might be useful in 
crises. We believe, however, that such measures have practically 
very limited application in view ofthe physical facts ofthesituation. 
Luxuries such as diamonds and platinum used for jewelry may 
well afford to pay import taxes. 
We would favor protection on domestic minerals known to exist 
in large quantities and capable of efficient utilization, but handi- 
capped in their competiton with foreign supplies by trade and 
technical customs. In these cases there should be careful consider- 
ation of possibilities of adapting our extensive low-grade reserves 
to our needs, wiıh a view of finding whether feasible and efficient 
165