F75 Question: High Mineralization Spot In My Backyard

[Birg]

Greetings!

I bought a F75 (basic) a few of weeks ago and am somewhat new to the hobby. I am still learning what my F75 is telling me and while I was sweeping in my back yard, I found a (hot?) spot where the Iron Mineralization level jumps from nothing to 0.3 on the Mineralization bar graph.

My soil is clay mixed with lots of crumbled rock (north central Maryland) and when I Ground Balance, I get a reading of about 55 to 65. I have tried searching in different modes (Discriminate w/ Sensitivity at 70, Disc at 18, Notch at 1, Tone at 4H and even Delta Pitch; All Metal-Motion) and my VDI registers nothing. In All Metal, I can hear a small Wow sound in pitch, but not enough to get a target ID.

What does this mean? Is it nothing to get excited about? Is it a mineralization halo from some iron object that has rusted completely away?

My whole yard registers nothing on the Mineralization bar graph, except for this one spot that seems to be about 6 inches in diameter.

I know the saying goes: When in doubt, dig it, but I don't want to start an excavation on much ado about nothing in my backyard.

Thanks!
Birg

 

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[Loco-Digger]

a 6" diameter plug is not that big and if dug properly (3 sided flap) will be dang near unnoticeable especially if you have a nice grassy yard. Dig the plug and report back as to what you find.

 

[G.A.P.metal]

My soil is clay mixed with lots of crumbled rock (north central Maryland) and when I Ground Balance, I get a reading of about 55 to 65. I have tried searching in different modes (Discriminate w/ Sensitivity at 70, Disc at 18, Notch at 1, Tone at 4H and even Delta Pitch; All Metal-Motion) and my VDI registers nothing. In All Metal, I can hear a small Wow sound in pitch, but not enough to get a target ID.

What does this mean?

Throw some coins on the ground and see if the machine can see them...or get #s
Gary

 

[Kray Gelder]

You found a spot where your mineralization bar jumps. You hear nothing, no VDI indication, tried different modes. It's NOTHING! Your F75 is a sensitive machine, and will sound of if a worm farts nearby ( not really ). But if you're not hearing or seeing anything, move on. Go dig some targets. You really have to put in the time. I'm getting the hang of mine, but no way would call myself an expert on it. Good luck to you, and have FUN. Remember, repeating VDI, both ways in a + pattern, dig it.

 

[vpnavy]

Greetings...(north central Maryland)...

I noticed this was your very first post - so, Welcome Aboard Birg! Take a look at Sub-Forums: Maryland for information (i.e., clubs, etc.) directly related to your state.

 

[Birg]

I noticed this was your very first post - so, Welcome Aboard Birg! Take a look at Sub-Forums: Maryland for information (i.e., clubs, etc.) directly related to your state.

Thank you for the welcome, vpnavy, and the advice Kray Gelder. I haven't dug up the hot spot yet, loco-digger. I have been living in this place for 15 years and I am pretty sure no one has metal detected it until now.

I tried your advice G.A.P.metal and tried a clad penny, a nickel, clad dime, a clad quarter, and my F75 picked them all out mostly with other jumpy readings. When I went to Fast Audio process, my F75 nailed them spot on, even from different sweeping angles.

While I was still in FA, I swept the spot again with no coins and noticed that I was getting a solid 1 on the VDI, but it was just the shortest, but very consistent "bip" sound.

To fill in a little more info, I have power power lines going through our neighbor's yard behind me which makes my F75 a bit jittery on all frequencies (F1-F7), so I had to turn my sensitivity down to about 65 to calm it down. Even so, at this lower setting, it seems to do better with the hot spot. Pinpoint mode indicates it is 5 inches down, which I don't believe. In Motion All Metal, the VDI won't register anything. When I pass the coil over the spot, the background hum goes silent.

I know I have a lot to learn yet about how to get my F75 setup properly, but this experiment has edged me a little further along to understanding the various tweaks, like manual ground balancing.

The mosquitoes were eating me alive out there so I had to quit for the day. I will go out and dig it when I can and let you know what does, or does not turn up. (I just wish I had a pinpointer!)

 

[miserman]

It's probably a "hot rock" that has a high concentration of minerals. It could also be a small area that had something burned there in the past,I have had that sound off before. Regardless It most likely isn't a "good" target. Congratulations on getting the F75. Good Luck on your finds.

 

[Rawhide]

Clay is rough bugger but hold targets for you. The F75 will detect voids, moved dirt, and old burn pits. I would dig and see if I found something so I know what that sound is. Sounds like a bottlecap to me or copper penny.

 

[Loco-Digger]

FA, JE, and BP modes are the most susceptible to emi, I'd switch to DE, also I only run sensitivity between 65 & 75 in town and near power lines.

 

[Charlie P. (NY)]

Welcome.

The mineralization scale looks for Magnetite (Fe304). But in my experience it will also climb in a spot where an iron object spent time rusting - like an old tractor part that was later removed. Rust is Fe2O, but also forms Fe3O4 in the soil.

Around here we also have iron in the soil and some red clay is naturally "rusty".

 

[chub]

FA, JE, and BP modes are the most susceptible to emi, I'd switch to DE, also I only run sensitivity between 65 & 75 in town and near power lines.

Below 30 is considered low sensativity on the F75. Even with sens at 31 its still a powerful detector but much quieter.
Always good to dig even the strangest signals when learning a new machine. As stated above, could be iron that is pretty much disolved but has left a halo.

Chub

 

[Birg]

a 6" diameter plug is not that big and if dug properly (3 sided flap) will be dang near unnoticeable especially if you have a nice grassy yard. Dig the plug and report back as to what you find.

This is for you, Loco-Digger. I dug up my mystery hot spot and found a hot rock; a rather large one. I posted a video on YouTube:

Thank you for all the helpful tips and comments, everyone. I really appreciate them!