which metal

[Brian L]

Hello Everyone,
I have been trying to figure out which metal my coins are
but I am not sure of a few,such as a

 Diocletian post reform radiate,I read that they aren't made of or coated with silver.
but looking closely,I see it is coated with something that chipped off in spots,
Does anybody know what this is?

What are 
Probus RIC 173 and Gordian III RIC 148 antoninii, made of

Thanks for the help guys

[Arminius]

Originally this had been coated by a silvered layer. But 1700 years in more or less humid soil  caused an oxidation process creating a brown mixture of metal oxides.

For the silver content of these read this thread: https://www.forumancientcoins.com/board/index.php?topic=446.msg3815#msg3815

regards

[Brian L]

Thanks Arminius,
I thought I read that Post Reform Radiates weren't coated with silver
may be I'm wrong.
I was hoping someone would  think it is patina,
as I am not sure what patina looks like.

[PeterD]

I think Brian is right. Post-reform radiates contained no silver and weren't "silvered", from what I've read.

An Antoninianus of Gordian III would have contained roughly 50% silver and probably have been "surfaced enriched". An Antoninianus would have contained roughly 5% silver and probably originally "silvered".

[Brian L]

This is my Gordian III,I am guessing that it is all silver

[Robert_Brenchley]

It's going to be fairly debased by that time, but I'm not sure of the proportions. This Postumus, which someone had abused with a wire brush before it came to me, shows pretty clearly the effect of surface enrichment. The pink is the sub-surface metal showing through.

[Vitruvius]

Hi Brian,

Patina is the oxidized metal that coats many ancient bronze and copper coins.  There is a decent dark patina displayed on your coin of Diocletian shown above.  Take a look at this link from Numiswiki for some great examples:

https://www.forumancientcoins.com/numiswiki/view.asp?key=Patina

I'm not sure I would be as thrilled about ancients if it wasn't for patina.  It can truly add alot of character to a coin, and make it truly unique.  I personally enjoy a sandy patina which really gives a great contrast.

[areich]

I don't know, I've had a few coins that had almost no patina (never had one as opposed to having theirs removed) and it's quite an attractive look also. But I agree, if they all looked like that,
it would be much less interesting.

Andreas