Strange iron like target not giving a signal mystery.

[Goldtarget]

I'll post a pic when I'm home but was digging a target and i piece of flat metal that appears to be rusting came out. Tried the vlf, nothing. Tried the pinpoint, same result. Double checked both with some other targets, perfect signals, thought for a moment i had two machines fail! Its flat and looks like steel right up to the rusting, but no signal. Any ideas? It has some bubble like markings which should come out in the pics later. Yet to test with a magnet, but its definitely "metallic" in its appearance. Pulled a piece of fencing wire out from below it.

 

[casper]

a UFO crash site for sure, might be worth millions that piece of scrap, I'd say nothing otherwise the KGB, Mossad, CIA ect will want it and ....
8.(

casper

 

[Tathradj]

Stainless steel ?
The modern imported version.

 

[Mr Boring]

I once had the bottom end of an old car aerial that was completely silent on a metal detector, It was shiny metal!! carried it around for years to spin out the old prospectors. Also, years ago I found a 1.5 gram sunbaker that hardly registered with my 3500 even though it was shining at me? weird hu..

 

[Goldtarget]

Being an ex metal recycler i took it home and did some testing, magnetic value extremely low, orange to white sparking, and although thin i cut it in two which revealed a "bronzing" layer in between. In the end to put my mind at rest I'll send it to get it tested for a definitive answer. Perhaps the oxidizing its suffered masks a signal, I surely do not profess to understand the inner electrical workings of a detector, so I'll rely on proven tech to get an answer, thinking perhaps a high maganese steel alloy that's suffered through heat treatment and oxidization hence not providing an impulse that my detector can read. Came from a mine Mullock, but who can tell where it came from originally.

I put it on the quietest ground i could find and it will break the threshold but barely. Whatever it turns out to be I'll be considering building a treasure chest out of it for backyard burial!