GARDNER, DAVID LEE

Ferromanganese nodules are small, irregular lumps of precipitated
metal oxides composed primarily of manganese, iron,
copper, cobalt, and nickel which accrete in deep ocean environments.
The nodules have mining value and commercial recovery
is expected in the near future. As present techniques for the
detection and evaluation of ferromanganese nodule deposits are
cumbersome and time consuming, an investigation of the specific
acoustic impedance of the nodules is conducted in an effort
to determine the feasibility of surveying ferromanganese nodule
deposits via side-scan sonar techniques. An acoustic transmission
line (impedance tube) is utilized to investigate the
specific acoustic impedance of the ferromanganese nodule
samples. The accuracy of the experimental technique is evaluated
using a steel reference cylinder. Results of the tests
(on the ferromanganese samples) indicate that the specific
acoustic impedance of a typical ferromanganese nodule sample is
2.07 +- .15 x 106 Rayls. Suggestions for future investigations
are also presented.