Bipolar Patinas

I guess you could call this the ancient version of end-roll toning? A very experienced dealer friend of mine explained to me that this sort of patina happens when the two sides of the coin are in contact with very different substances, ie. the clay of a pot on one side and metal coins on the other. It sounds reasonable enough to me.

Here's a litra of Sicily that just arrived yesterday. Athena has a dark olive patina with highlights of brass, while the hippocamp is covered in turquoise...



Some 20 years ago I went on a hiking expedition in the Andes, and the color of the reverse reminds me of the the color of the isolated, hypersaline lakes one comes across in that neck of the woods...



Anyway, post any coins you might have with bipolar patinas, and any theories you might have as to how they get that way.

 

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Very cool, but nary a bipolar in my stables!

 

kool coin! but as far as i know, i'm the only thing that's bipolar in my collection

 

So different. Nice anyway

 

its a "reverse able" coin

 

I buy your dealer friend's explanation. Here's a Lucius Verus sestertius with two distinctly different patinas. I picked it up in an auction that featured quite a few other Antonine bronzes with bipolar patinas, clearly all from the same hoard.

 

almost bipolar patinas Claudius

 

That's really cool!!

I'm not aware that I have any of the 'type' remaining in my present collection.

 

A very nice coin @John Anthony . You always get the good stuff.

However, be careful with those lakes, less Pluto's toxic breath rob you of life. Some have been known to belch toxic clouds of CO2 and kill hundreds of people. Truly the doorways to Hades if you ask me. Take care not to find yourself enjoying sight of blue waters one second, and crossing the river Styx the next.

One of those volcanic lakes killed 1,700 people in 1986:
http://science.howstuffworks.com/environmental/earth/geophysics/lake-nyos.htm

 

I remember when that story first aired - one of those reality is stranger than fiction stories. Crazy.

 

neat JA, it's a great looking coin....the color of both sides is pretty.

the only think i have kind of like that is these two coins..




When I first got them they were stuck together!

 

Haven't gotten this one in hand yet but I think it qualifies. I liked the portrait so much I bought it in spite of the reverse.



Antoninus Pius. AD 138-161. Æ Sestertius (33mm, 27.31 g, 12h). Rome mint. Struck AD 155. Laureate head right / Libertas standing left, holding pileus and vindicta. RIC III 929; Banti 227. VF, brown patina with areas of green deposits, some roughness.

 

I think most of us have atleast one in our collections.

 

Here's an odd one of Termessos Major, it doesn't look like it's of the same coin.

 

I got this attractive Augustus, with a light pinky/brown reverse and blue/green shades, brown hair and a couple of specs of red oxide or something on obverse, haven't got a clue why it's like that but makes for an interesting coin.

 

the original hulk?!?..

 

Very mottled patina on this dupondius of Antonia:

 

Very neat, and great coin!

 

Ummm, maybe there was a bit more manure on the obverse-side?

 

This one has always been one of my favorites from your collection. Pass the manure, please .