Coinage shapes

[1] There is a list with more unusual shapes of non-circulating commemorative coins at the end of this page, that all have been issued officially by various countries.

The Cook Islands have a circulating 2 dollar triangular coin with rounded corners.

[12][13] In 2014 Transnistria was the next country to issue a circulating pentagonal 5 rubles hard plastic coin.

[14] The Belgian Congo had a hexagonal 2 franc coin,[15] as did the Kingdom of Egypt (2 piastres, also known as 2 qirsh).

Reuleaux polygons have constant width, which means the currency detectors in coin-operated machines do not need an extra mechanism to detect shape.

[32] Currently, the Philippines issues nonagonal 5-peso coins from 2019 as an enhanced design of the round version to make it distinct from the other denominations.

[35] Some other countries that have issued ten-sided circulation coins are Chile,[36] the Dominican Republic,[37] Jamaica[38] and Madagascar.

In some countries this was to allow them to be strung together,[54] while other reasons include difficulty of counterfeiting and ability for visually impaired people to distinguish them from other coins.

[57] Due to the soft metal tin used to make these thin old coins, they can easily be bent.

[67] The Isle of Man has some triangular special issue coins where the triangle is not regular (the angles are not all 60 degrees).

[69] Tetradecagonal: In 1976, Malaysia was the first country to issue 14-sided coins, the non-circulating 10 (silver) and 200 (gold) ringgit.

[70] Australia started to issue a series of non-circulating 14-sided 50 cents coins dedicated to the Chinese zodiac in 2012.

[76] Spheres: Niue issued the first official (non-circulating) spherical coin with a face value of 7 New Zealand dollars.

[79] Arc (section of a circle with a hole): China started to issue a series of arc-shaped coins in the year 2000.