Firstly sorry if i’m posting in the wrong place - still finding my way around this site but everyone has been very welcoming!

I am a young collector and this is the second medal i have purchased, from Phoenix Militaria in London - Ivor was nice enough to let me photograph a few of his items and we had a nice chat,

But i have my reservations about the Ostmedaille i purchased
can anyone help ? i’m assuming it is not zinc because there are no bubbles present.
The surface looks sort of strange and scratched ?

Any help much appreciated, i know it is a very common medal.

Click to enlarge the picture