Japan, Akita, cast 100 Mon. Off Metal counterfeit? :contemporary or otherwise?

   We have what appears to be a Japanese cast coin.  Much pertinent information is provided.  The following is relevant.

     This is dated 1862.  The cast coin has smooth surfaces exemplary of a quality casting.  No air bubbles or similar. Non-porous.

  The coin weight is: 38.1 grams.  The net estimated volume: 5.4 cm³   (adjusted for recessed fields and the hole  from 5.4 cm³ to 5.0 cm³ ).

NGC and Krause (KM-8) say it comes as a lead casting with a copper plating..   If it were lead, it would weigh 40% more than this  Roughly 51 grams.. 

The density of lead is 11.3 grams per cm³    

Iron is 7.9 grams/cm³     but it is non-magnetic

and copper is 9 grams per cm³.               Here we have 7.6 grams per cubic centimeter.

 Visually, it appears to be copper (or copper alloy which is the best shot at identifying this)

The specimen in Numista leaves me with questions.

 Comparison to others (see Ebay, etc) might help.

In order to allow this inquiry to bear fruit, I have several questions. 

      1.)  The density of the coin and other noted factors leave us with a great liklihood that this piece is a copper alloy.. 

              If we assume so, can anyone provide us with other similar specimens to compare to?

              Does anyone have knowledge of copper alloys being used at this point in time?    (1860's)

       2)   There is always uncertainty surrounding  cast coins because most of us are unfamiliar with these.

       3)   Possibly the name and email/text of someone who could clarify this.

       4)   Anything else that might shed light on this piece. 

Many thanks for looking 

posting by magic steve.

This is clearly a modern forgery. Genuine specimens are copper alloys containing high lead content and do not exhibit this coloration.
Since copper has been used in Japan since ancient times, there is no doubt this is a copper alloy. However, copper from the Tohoku region contains high lead content, resulting in either a reddish hue or a crumbling, brittle texture.
I apologize, but I do not possess a specimen. However, having seen numerous genuine specimens, I can confirm this is a modern forgery.

Feel free to ask me anything. (When it comes to Japanese coins, I know almost everything.)

Indeed it is far to smooth. We had in the past pictures from a specimen that looked similar to yours (maybe a bit more convincing) from Heritage Auctions and it was also a fake stated by Stephen Album.

@okedo I never seen one IRL so I have to rely on what I read. Do you have any sources were it states they are out of a uniform copper-lead alloy? My sources say these coins exist in either lead or lead with a thin copper surface.

Idolenz

Indeed it is far to smooth. We had in the past pictures from a specimen that looked similar to yours (maybe a bit more convincing) from Heritage Auctions and it was also a fake stated by Stephen Album.

 

@okedo I never seen one IRL so I have to rely on what I read. Do you have any sources were it states they are out of a uniform copper-lead alloy? My sources say these coins exist in either lead or lead with a thin copper surface.

https://shushu.co.jp/wp-content/uploads/2024/04/2405douzan.pdf

According to this, the ratio of copper to lead is 8:2.
Most records concerning these Japanese domain tokens were burned to avoid detection by the Edo shogunate, so I believe detailed records have largely been lost. Therefore, I think this is merely an estimate arrived at by Japanese numismatists over many years.

Makes sense, copper and lead don't really are able to form alloys unless one of them is present in overwhelming majority. Thank you.