Mumon-ginsen Coin (無文銀銭)
Mumon-ginsen coin is the Japan's oldest private silver coin.
Some people argue that Mumon-ginsen coin was not 'a coin,' because it was practically exchanged based on the value of bare metal (In western Japan, silver Hyoryo kahei coins [currency valued by weight] such as mameitagin [an Edo-period coin] and Chogin [collective term of silver] were used even in the later Edo period.)
Mumon-ginsen coin has a diameter of approx. 3cm, and a thickness of approx. 2mm, with a weight of approx. 8-10g (It is equivalent to 6 shu [one ryo = 24 shu] which is one fourth of one ryo in the ancient times.)
Totally 120 Mumon-ginsen coins are excavated from seventeen sites around Japan including seven places in Yamato Province, six places in Omi Province and each one of the places in Settsu Province, Kawachi Province, Yamashiro Province and Ise Province.
Mumon-ginsen coins are made by cutting a silver plate and has no square hole that is characteristic of old coins but has a small round hole.
Most Mumon-ginsen coins have no coins name inscriptions like 'Wado-kaichin,' but some Mumon-ginsen coins have inscriptions such as 'Koshi,' 'Ban' and 'Dai.'
Many Mumon-ginsen coins have pieces of silver pasted on to adjust the weight.
There is a view that Mumon-ginsen coins were silver coins circulated before Fuhonsen coins, because in "the Nihonshoki" (Chronicles of Japan) it says in 683, 'Do not use silver coins but use bronze coins hereafter.'
There is also an opinion that mintage of Mumon-ginsen coins had something to do with the fact that silver coins of Wado-kaichin were issued before bronze Wado-kaichin coins.
And there is another view that silver coins were used around those times when the article of October 6, 486 in "the Nihonshoki" mentioned that 'one rice koku corresponds to one mon silver coin.'