I see nothing that makes me doubt authenticity. I don't know whay it looks so silvery, I would gently rub it with some white spirit or bathe it in acetone for a while. But this is either a remnant of cleaning or an artefact of photography. The coin itself looks fine to me.
Thanks, a coin seams was covered by sulfuric ointment
to made it in one color, think because partly it has traces of burning
Can't find this
type in the internet.