Detecting through rock

[Bigdogdad]

I have some locations I am working on. It is possible that what I am looking for is under rock. I have a Garrett GTI 2500. I am wanting to know how much solid rock affects the ability of this or other metal detectors. Would a foot or two of rock stop a metal detecting from sensing something under it? If a large amount of gold or silver was covered by a large rock would it make it hard or impossible to detect through it?

 

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[Tom_in_CA]

Detecting through rock is no different than detecting through ground . Depth ability would just depend on the detector , the size object , & the minerals .

 

[coin hunter]

I have found two old coins (1803, 1800 copper) in the past using my 2500 that were under a flat rock ,that was in a farm field. 6 to 8 inches.

 

[GrizLeeBear]

I have thye GTI 1500 and I am searching every day under rocks and stones out here in SW Texas. I still find things. I would say the size and composition of the rock would be a factor. In my area when I get a hit I scrape the surface and sweep again. This often changes the signal.

 

[63bkpkr]

bigdogdad,
First that is an interesting name you have! Second when I'm out prospecting I find tiny pieces of gold under 6 to 8" of solid stone so yes a detector will read right through stone. How deep the detector will read a metal object depends on the detector itself, the mineralization of the ground, how deep the target is, the size of the target, what metal the target is and how much of the target has been absorbed into the dirt around it, I believe this is called a Corona effect (different than the effect of drinking several Corona's). Good luck on your search and if you think it is the right spot then dig.........63bkpkr

 

[spartacus53]

I'd just move the rock, then detect Better yet, find a rock free area

 

[63bkpkr]

Spartacus that takes all the fun out of it!...........63bkpkr

 

[bustinloose]

bigdogdad,
First that is an interesting name you have! Second when I'm out prospecting I find tiny pieces of gold under 6 to 8" of solid stone so yes a detector will read right through stone. How deep the detector will read a metal object depends on the detector itself, the mineralization of the ground, how deep the target is, the size of the target, what metal the target is and how much of the target has been absorbed into the dirt around it, I believe this is called a Corona effect (different than the effect of drinking several Corona's). Good luck on your search and if you think it is the right spot then dig.........63bkpkr

what kind of detector do you have

 

[DDancer]

Corona or Halo effect is caused by the leaching of metals off the detected target into the surrounding soil causing a slightly larger area of conductivity around the metal target. This differs from metal to metal and is more pronounced with metals that have a high chemical reactivity to acids and alkaline in the soil. Copper, silver and especially iron can exhibit large Halo's. Less pure gold will exhibit the effect as well due to leaching of copper and silver from the base metal. Pure gold will not exhibit a halo as it has no reactivity with the surrounding soil.

Mineralization and rock density do attenuate the signal from a metal detector and will limit the signals penetration, ie depth, to some degree. Mineralization is the more pronounced limiter because it messes with GB and acts much like a metal plate masking targets at depth. Rock density will also limit the punch of a detector but does not tend to mess with GB. Vlf machiens are more affected by mineralization and density than PI detectors so if you want to detect hard rock at depth I would recommend a PI. The 2500 is a very good machine however Good luck.