TID For A Mason Jar Coin Cache?

[Caliche]

Anyone know what a Mason jar of silver coins would sound and look like on the 2D? 

Unless it was deep, seems like so much silver would overload the machine, and the steel cap would skew the target toward iron region.  Any experience with it?

[GB_Amateur]

1 hour ago, Caliche said:

...The steel cap would skew the target toward iron region.

If it's been in the ground a while (say prior to 1960) the lid would likely be zinc.  I've found several (lids, not caches ) which seem to ring up around where fresh Zincolns hit.  I don't think I've detected a zinc lid with the Manticore yet, though; but quite a few with the Equinox.

As far as how the contents affect the overall signal, I have no idea but I'm curious.   (My memory says Carl has addressed this in his new book,...  I'll see if I can find that mention.*)

Addendum:  *On pages 86-87 he talks about a test he did with plastic container of 220 silver quarters, but his conclusion is not really applicable to your question.  Here's a thought if you have a bunch of silver coins and a zinc lid -- do a test yourself!

(Note:  I hesitate to say too much about specifics in the book.  Every serious detectorist should own this and buying one is a sign of gratitude for someone -- an expert -- who answers a lot of questions here, for free.)

[Doc Bach]

9 hours ago, Caliche said:

Anyone know what a Mason jar of silver coins would sound and look like on the 2D? 

Unless it was deep, seems like so much silver would overload the machine, and the steel cap would skew the target toward iron region.  Any experience with it?

Unless the jar is modern the closure would be made out of zinc.😊

[EL NINO77]

First of all, you should make a simulation of such a container filled with the appropriate coins - and test it in airtest..what VDI and at what distance can you detect such a container in airtest..

use multifrequency,,what also try to use  1F low frequency say 5 and 10 ...khz..

Here you will see at what distance you can detect such a container with coins..

That is the first assumption how the detector will react to such an object...

Further testing in the ground will be more demanding because .... the terrain can negatively affect and further reduce the depth of detection for this type of object...

[TampaBayBrad]

OP sounds like he got a tip as to where a jar of coins may be buried. 🤔

[Caliche]

^ Unfortunately not, but I'd sure hate to walk away from one thinking it's just a beer can, lol.  Maybe the zinc lid would stretch the trace into a horizontal blob from 55 to 80.

Guess I need buy a zinc top jar and bag of junk silver coins, I don't have many.

[Geotech]

On 1/19/2025 at 9:36 AM, Caliche said:

Anyone know what a Mason jar of silver coins would sound and look like on the 2D? 

Unless it was deep, seems like so much silver would overload the machine, and the steel cap would skew the target toward iron region.  Any experience with it?

You'd be surprised at how hard a jar of coins can be to detect. The zinc lid just might be the strongest signal at any depth. Generally, if all the coins are silver (dimes through dollars) then their composite signal will be in the upper silver range. Don't know where a zinc lid lands, GB_A's suggestion of around a zinc cent may be right, though I would have expected a bit higher since the lid is physically larger.

[Caliche]

3 hours ago, Geotech said:

You'd be surprised at how hard a jar of coins can be to detect. The zinc lid just might be the strongest signal at any depth.

Was thinking that might be the case, especially if the aggregate coins behave like links in a gold chain, i.e. reads more like an individual link than it does the total chain mass because there isn't ideal conductivity between links.  Maybe there's less of this effect with silver due to higher conductivity, or if the coins are a more recent cache and are tightly rolled.

[GB_Amateur]

10 hours ago, Geotech said:

GB_A's suggestion of around a zinc cent may be right, though I would have expected a bit higher since the lid is physically larger.

Surprised me too.  I recall at least two coming in around 22 on the ML Equinox (ID of a fresh Zincoln and well below 95% copper 1960's Lincoln which shows up 25-26 typically).  Here are some thoughts as to why, in no particular order:

1) VDI possibly dragged down by nearby iron (but would have had to have happened at least twice...), maybe even ground conditions and signal/noise strength could contribute;

2) Are zinc lids pure zinc, or some kind of alloy?

3) The lids I've found have been buried for decades.  Corrosion *can* lead to VDI degradation.  Most (all?) of the ones I've dug are not in pristine condition, often with part of the rim broken away.

4) I've misread the VDI, or possibly don't remember as well as I think I do.

Besides the ones I've dug (which are still around in my misc. finds 'collection'), I have a few never buried ones from my Mom who was both a canner AND a packrat.  (I've inherited that trait honestly.)  😉      

For a while I've been planning on burying a (recovered) zinc lid about 10" deep in my back yard as part of my growing test garden.  Maybe I'll put one deeper, too.  However I have no plans of burying silver with it, although I certainly can do some testing with silver coins under the lid before I fill the hole -- sort of a hybrid air+in-ground test.