Handling Hot Rocks with X-70

[Montana Tracker]

I have been using the '70 for about a year now and like every thing about it. However, my new prospecting spot has a lot of hot rocks in it. That and some overburden equals a bit of digging. I know that a PI would be the answer but it's a poor carpenter who blames his tools. I use both the 5x10 and the 6 in which allows me to work around some of them. I would like to hear how you more experienced users deal with this problem. The ground balance is between 18 and 24 most of the time.
Thanks

 

[nugget71]

if your hunting where iron stone is abundant then be careful using this method as some species contain iron as you probably know, and you may miss a target. If it reads -8 in all metal it usually means hot rock, sometimes -8 / 48 will also occur. Just switch from prospect mode to all metal from time to time on iffy targets. Check your tracking, and GB frequently too. I took my 70 to an ancient river bed once and tried using it in prospect mode and ended up using all metal mode because every second sweep I was getting a reading of -8. I was using the elliptical DD coil at the time too. That is one area I will not be going back with the 70 :veryangry: but hey I did end up finding a nice old swiss army blade that day. The blade was blunt and a bit rusty but after I gave it a clean and sharpen it was like new. Oh yea I had my sensitivity turned down to about 18 that day but didn't seem to make any difference where hot rocks were concerned. One last thing too slow down your sweep speed in prospect mode you will be surprised with the results.
Cheers!

 

[BarnacleBill]

A few things come to mind that may or may not help. On the smaller surface hot rocks, raising the coil and comparing that to how small gold would attenuate may provide a clue. On the larger pieces size & shape may help, especially comparing the edges of a large object, hot rocks tend to have "soft" edges. Approaching the target from 90 degs, hot rocks are pretty variable. Lastly I'd get a GB number for the background ground matrix, get a GB number off of several of the larger hot rocks(choose those that about the size of the coil or larger) and then manually set the GB in between those values and see how the detector reacts. You may have to back the sensitivity down a little to deal with a poorer match against the background matrix, but it may help your overall reaction to hot rocks. I've also found slowing down the sweep provides some clues, good targets react quickly on audio ramp up and down, whereas hot rocks can be kinda mushy.

HH
BarnacleBill

 

[Montana Tracker]

Thank you for your suggestions I will try them the next time out. I hate to pass on this creek as it has promise, although small stuff. The small coil lets you work around some of it and you are right about speed some times it has to be real slow.

 

[B.T]

Takes practice and you have to be careful, trial and error, but some or many will disc out in coin relic mode. Some do have gold in them, you need to learn the diff in sound to those with and those without.

 

[Montana Tracker]

Thanks again for everyones help. Will try to come up with something worth a post.

 

[nero_design]

I used a Vibraprobe Pinpointer 570 the other day in VERY hot soil. Whilst my X-Terra was detecting ironstones and similar, the Pinpointer would also respond to the same... and even more. Now the 570 is a Pulse Induction device. But both the X-Terra 70 AND the GPX-4000 (a Pulse Induction 'Super Gold Detector') are similarly fooled by mineralized runoff on certain soils... so don't feel you're at too much of a disadvantage!