Nope. 1/24 Thaler is billon actually, although the alloys back then were sometimes pretty bad.
The averse clearly looks like 1/24 Thaler or 1/48 Thaler (compare with the one the bottom here:
http://oldgermancoins.com/prussia-124-thaler/), but the reverse reminds me of Polish grossus (Groschen/Grosz) coins.
There are several possibilites now...
1. It could be a contemporary error of someone mixing up the dies. However, Prussian 1/24 Thalers and 1/48 Thalers were in Poland minted in Königsberg and I cannot think of any reason why they would have had Polish dies over there.
2. It could be some kind of contemporary private production, made as a souvenir.
3. It could as well be a modern counterfeit. The bubbly surface looks to me as if this one was casted.
Personally, I think option #2 is the most likely one...
Edit: I'll check my catalogue later. If I'm not wrong, Prussia did actually mint Groschen coins in West Prussia that look like the reverse of yours... They were also made of copper if I remember correctly. Could you please provide size and weight of your coin?
Edited by Potsdam
03/16/2017 3:11 pm