Whispering Caprock

Good day from WA,
Hello everybody. I've come across a cap rock signal this season that is somewhat puzzling. It comes from extremely hard conglomerate, adjacent to a creek bed, and I have not yet started work on it as I first need to get permission for that spot on an existing mining lease.
  Firstly, the signal changes considerably when tested at 90*; from short to long. Secondly, in normal timing (on a 5k with med. size mono) the signal breaks up in both directions, similarly in sharp and salt. The best response is obtained when using fine gold, and  enhance is not far behind. I've tested five different coils on the target, including an 18in Commander DD with very disappointing results. The best response comes from a 17x11in Nugget Finder.
  I assume the target could be an irregular, blob of gold (or other metal), finely distributed in rock, not dense enough to register properly in normal timing. I've camouflaged the area well for the summer, and hope, with approval, to chisel the mysterious object out early next season.
  I would appreciate your thoughts.
Regards, STEADY EDDIE