Half penny madness. [gelöst]

I have in my possession a odd little 1971 half penny. To put it simply its silver tone. Il included pictures next to a normal 71' halfpenny. Additionally I weighed them on accurate scales and found the normal one was 1.77g whereas the odd silver tone one is 1.82g. What's the score….. Is this a off metal strike, has it been guilded or plated etc…. The details look the same quality on both pieces. And lastly what would you think it's worth? 

Thanks for any replies, as always it's much appreciated. 

Somebody plated it, like many times discussed here before, on other occasions
It is worth what someone like to pay, I am afraid it will be not much.

The process is called electrolysis, everybody learned about that in school, I suppose?

Sjoelund

The process is called electrolysis, everybody learned about that in school, I suppose?

Good manners…. I thought everyone learned about those in school. It's evident you'd didn't.