Variations In USA Small Cent Compositions (in 3 Posts, Including A Summary)

[kac]

Interesting charts. There could be variations in the same year as different die's, die pressure and possibly variations in the alloying of the planchets.

[mh9162013]

Great testing and thanks for sharing your results!

One thing I found interesting was the 25 TID readings on many of your 1944-1982 pennies.

In my parks, a lot of my pennies are either Zincolns (no surprise) and copper pennies from the 1960s to 1980s. It's this latter group that often ring up at with a VDI/TID that was seemingly closer to a dime instead of a penny. I've assumed my ground balance was a smidge off, but it looks like it might not be me.

[GB_Amateur]

2 hours ago, mh9162013 said:

It's this latter group that often ring up at with a VDI/TID that was seemingly closer to a dime instead of a penny.

With my ML Eqx 800 in my ground I typically can't tell the difference between a 95% copper Memorial cent and a clad dime.  Maybe some detectors can....  As depth gets down to more than ~5 inches, the spread of dTID's for a single target gets larger.  It stills tend to have a central value about where a similar shallow target would, but IMO it's a mistake to get too picky.

Some people talk about trying to tell the difference between a clad dime and a silver dime by looking at the dTID.  That may be easy to do on an air test at a few inches, but again, targets in the ground are in a different class.

Now, for early Lincolns, IHP's, and Zincolns, similar issues apply.  Sometimes (especially near the end of a detecting session when I'm getting tired) I will ignore shallow targets in this range figuring they are Zincolns.  But in the long run I will get burned by that practice.  I recall finding an IHP at 3 inches depth.  I've found 2 inch deep silver dimes.

[kac]

What about the F75, it has a wider set of #'s that should show more subtle differences.

[GB_Amateur]

1 hour ago, kac said:

What about the F75, it has a wider set of #'s that should show more subtle differences.

Yes, I thought about that after I got started, but since I spent ~10 days (~couple hours a day) on this study I just ran out of steam. 😁

More people have Equinox so I figured that was relevant.  Also, there have been some (Steve H. being one) who argue that just because you have more bins doesn't mean you get higher resolution.  Where the target falls on the scale may also make a bit of a difference although the ML Eqx and Fisher F75 have USA cents falling at about the same region on their full non-ferrous part of scale, so probably not a big deal there.  There are probably other subtle differences which might show a bit of variation with this kind of test.

But, yes, I was going to use the F75 to search for a difference between the 1% tin, 4% zinc of 1947-1961 and the 0% tin, 5% zinc of coins minted during and just after WWII and also the 1962-82 Memorials which also had no tin.  If you recall there was no apparent dTID difference from WWII onward (using the Eqx).  Is there something else that better resolution would reveal?

Bottom line is that by the end of my study I needed the tables for other tasks!

[kac]

Not that either machine doesn't have the resolution but the having a wider range of numbers will give you finer divisions. Like having a 3/4 turn pot vs a 1 or 3 3/4 or 5 etc