38 
OUR MINERAL RESERVES. 
should be adaptable for crucible making. Although the deposit does 
not compare in size with the Ceylon deposits, it might render mate 
rial aid in case of a shortage. 
The graphite deposits of the United States are fully described in 
a report by Edson S. Bastin on the production of graphite in 1913, 
recently issued by this Survey. 
FLINT. 
In 1913 nearly $320,000 worth of flint pebbles was imported into 
the United States, mainly from Denmark and France. In these 
countries the flint occurs as irregular nodules in the chalk cliffs that 
border certain parts of the coast, and under the impact of the waves 
the hard flint nodules become freed from their relatively soft chalk 
matrix and are gathered in great quantities from the beaches for 
shipment to various parts of the world. After reaching their desti 
nation the more irregular nodules are calcined and ground to a fine 
powder for use in pottery manufacture, but those that have been well 
rounded by the waves are reserved for use in tube mills, their hard 
ness and chemical inertness making them a desirable grinding agent. 
The cutting off of the imports of flint pebbles should work no 
material hardship to the pottery industry, as that industry uses only 
subordinate amounts of flint compared with the crystalline quartz 
obtained in Connecticut, New York, and Maryland, and as the supply 
of the quartz is far in excess of the present demands. A cutting off 
of the supply of rounded flint pebbles suitable for tube-mill use 
would probably entail some inconvenience, for so far as is known we 
have no flint deposits that are comparable in both quality and quan 
tity of material with the foreign supplies or that could compete 
with them (except perhaps locally) under ordinary conditions of 
uninterrupted foreign commerce. 
On account of the high quality of the foreign flints and the cheap 
ness with which they can be brought into this country, little attempt 
has been made either by the Survey geologists or by dealers in flint 
to investigate the domestic sources. Deposits of flint pebbles have 
been observed at several localities in this country in the course of the 
geologic surveys, but they have seldom been examined with especial 
view to the possible utilization of the flints in tube mills. The 
information available is therefore fragmentary and may, at the most, 
serve only as a guide to further prospecting and testing. 
The principal localities at which flint pebbles have been noted in 
particular abundance are all in the Gulf States. The pebbles occur 
mainly in gravel beds, and only part of them are well rounded. In 
some places the gravels are stained and partly cemented by oxides of 
iron, but elsewhere they appear to be fairly free from iron.