Take the total weight of a silver dollar and subtract 10% - then take that 10% of total weight in copper and turn it to dust. Then sprinkle it in the dirt and water it. Do you hear it with your detector? Nope - so not even a SILVER DOLLAR's worth of copper (or tin or nickel) could be heard. How would a dime's material be heard - or EVEN increase the detectability of a coin? It's a bad argrument for folks explaining a bogus depth claim or discrediting air testing (FOR DEPTH) in defense of the detector they chose. What could be cleaner than air when using electromagnetic fields?
Do this - take a dime and place a penny next to it. That's roughly 150% of added copper. Bury them side by side at 14"... did it help? Even better, smash the whole dollar above to dust, sprinkle it in the ground, water it, freeze it, thaw it, put a few earthworms through it, shake it up, etc. for 5 years, and see if you hear it....
Even though the "halo effect" of precious metals is way over stated and without any scientific basis WHENrelated to a VLF detector, I'll concede the argument and allow you to show us an air test of a quarter at 14".... Surely, you recognize that no amount of "halo-ing" could make a dime the size of a quarter, so that video would be nice to see as well.
Claims like the one in this thread are reckless and cause folks to make bad decisions when picking out a detector. It does the hobby an injustice, but so does the halo argument.....so....