The soil here is up in mineralized area Mxt readings on 9 inch coil 74 to 80 gnd.if that helps .The big coil is hot you can go over a area with stock and think you cleaned it out and come back though and start pickling up coins again.Has pretty good separation and covers a big area and it will hit on small stuff to. The depth i will say a hot wheel car or anything flat that size 11" to 11 half in ground, Now coins it will hit Penny's at 9 to 10 it hits hard on quarters will get them deep dimes to. It will find them if part hidden by rocks or if trash near by and iron just half to listen and ferret it out.I notice when coin is real deep it will bell tone break bell tone kind of like it is hidden it is usually deep and if you hear it for sure and its deep but lose it after digging keep looking it is there use pinpoint or all metal if it is not in dug dirt it is still in hole don't give up if you knew for sure something was there.Use the 9x12 more than stock only little heaver.Hope this help some.Tvanwho seen your ? on xterra forum that is probably good machine.But the ace 250 will give 600 dollar detectors a run for there money 250 is good back up and fun to use even as main detector .Also no matter what machine you clear a area with someone can come through with a different machine and still get coins.You usually never get it all.Different size coils different machines.Hope this helps.Good luck and good hunting