I know what you are saying DDF, BUT--the really scratchy mid to upper 70's are generally rotting zincolns, but if it sounds fairly clean, DIG THE DARN THING!!. the sound can be saying the density is not uniform, meaning JEWELRY. copper cents, clad and silver dimes at this site all hit between 78 to 82 due to the clay and iron levels. clad is coming out green to orange and a few silvers were rusty and or black stained. there are some decent sounding high 60's there that are likely brass that have me interested, will try digging a few since IH's hit there but this field does not have the history for them and depth is less than a foot. back again today