http://content.liveauctioneers.com/item/6040617 - pattern http://www.anythinganywhere.com/commerce/exo/ger-medal.htm - 4th from last pic. op 386 or 387 contents lists it as op 387, but the pic in the book (The Medals of Karl Goetz By Gunter W. Kienast) is op 386. A German 5 mark Weimar Republic by Karl Goetz of President Hindenburg's 80th birthday 1847-1927, weight 17gms approx, dial 36mm.
This was the only info I could find. http://www.coinarchives.com/w/lotviewer.php?LotID=297962&AucID=219&Lot=3106 I usually dont buy coins or medals after the year 1918. But I liked the detail on the rev. of this.
It's not really a 5 Marks coin, it just has the same composition and weight, but it's not legal tender I think. Edit: "Goetz created an actual 5 Mark pattern for competition for a new coin (probably 5 made and very expensive) but the Munich Mint did not pick his design. It was suggested to him that he convert the pattern to a commemorative medal in order to recoup his costs for time and materials on his original design. He then did so and it is the most prevalent medal he made with over 1 million in circulation. The current price (approx $50) is it's value." This is taken from a personal communication.
Quite similar to the the 1927 medal. Judging from the "Bernhart" signature, however, I suppose this '28 pieces was designed by Josef Bernhart. Christian