While I am no expert either, it does look like a good Klein & Quenzer A.G. to me. I don't think they are all that uncommon, but wouldn't call them exactly common, either.
It's a late war zincer that's more or less textbook with typical streaking as the finish disappears.
'I do not think we can hope for any better thing now.
We shall stick it out to the end, but we are getting weaker of course, and the end cannot be far.
It seems a pity, but I do not think I can write more. R. SCOTT.
Last Entry - For God's sake look after our people.'
In memory of Capt. Robert Falcon Scott, Edward Wilson, Henry Bowers, Lawrence Oates and Edgar Evans. South Pole Expedition, 30th March 1912.
Nice looking example for a zincer, certainly not rare. Don't let the seller try to convince you otherwise.
nice silver award in zinc.