[ adjective ] hard as granite
"a granitic fist"
Used in print(Cornell H. Mayer, "Radio Emission of the Moon...)
Piddington and Minnett explained their observations by pointing_out that rocklike materials which are likely to make_up the surface of the moon would be partially transparent to radio_waves , although opaque to infrared_radiation .
Since the absorption of radio_waves in rocklike material varies with wave_length , it should be possible to sample the temperature variation at different depths beneath the surface and possibly detect changes in the structure or composition of the lunar surface material .