Please identify Argentina coin - not in catalogue

Hello
I have this Argentina 1 peso coin 1981 year commemorative of 100th anniversary to peso.
This coin not in catalogue Krause
This coin not in catalogue Krause unusual
Please help - if this is real coin or fake?

Weight 27,30 gr, metal - silver, diameter - 37,5 mm

  Welcome to the site.  
According to the page below it is not a coin but a commemorative medallion.

http://articulo.mercadolibre.com.ar/MLA-495863679-patacon-medalla-conmemorativa-a-su-centenario-1881-1981-_JM

 That page is in Spanish, and they show a copper version, so yours is the silver version (or yours could be copper underneath but silver plated by someone). Perhaps - that was the only page I could find.  

Citeer: ZacUKWelcome to the site.  
According to the page below it is not a coin but a commemorative medallion.

http://articulo.mercadolibre.com.ar/MLA-495863679-patacon-medalla-conmemorativa-a-su-centenario-1881-1981-_JM

 That page is in Spanish, and they show a copper version, so yours is the silver version (or yours could be copper underneath but silver plated by someone). Perhaps - that was the only page I could find.  

thank you very much!
but my coin weight 27,30 gr. you think possible to plated and add 4 gr weight?

  I do not think so; so yours may be all silver. I still look but only find that one page for now.