a small coin with only a date

I found this small coin (diam. aprox. 14mm) with only a year 1658. On the top I recognize only a H. The reverse side is flat.

What is it?

Hello,
It's a coin of 3 heller probably minted in the Archbishopric of Mainz under Johann Philipp von Schönborn in 1658, but I couldn't find any informations about it.

I think the coat of arms represents the city of Mainz on the left, the counts of Schönborn (bottom) and Johan Philipp on the right (or maybe something related to his mother's family as it's present on his coat of arms).

We can find those elements here with his Archbishopric title on it (the key) :
https://www.ngccoin.com/price-guide/world/german-states-mainz-thaler-km-110-1658-cuid-1159118-duid-1388772

Might be of some help. In the top left Coat of Arms is Mainz, top right is the Duchy of Franken. The center bottom is hard to make out but almost looks like Bayern ...

Perhaps Arie can help:
http://www.bonatiele.nl/

Very nice coin!

https://www.numisbids.com/n.php?p=lot&sid=1489&lot=1710

I would say this would be Würzburg. In addition to being Archbishop of Mainz (1647~1673} Johann Philipp was earlier Bishop of Würzburg from 1642~73, among other titles. The arms to right represent Würzburg/Franken ( Würzburg located within Franken~ Schönborn family lands) Coins for Mainz I think use a more elaborate set of arms. And as Cycnos stated, Schönborn arms at bottom.
Cycnos was on the right path, although I also cannot find this coin. Also a different denomination, the closest I can find is this: https://www.ma-shops.com/saenn/item.php?id=25017
Hope this helps somewhat

I don‘t think I have this book but if someone has we should check there:
würzburger münzen medaillen 1500 1800 von helmschrott klaus