Coinage shapes

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The Tenpō Tsūhō, a Japanese coin from the 19th-century.

Although the vast majority of coins are round, coins are made in a variety of other shapes, including, squares, diamonds, hexagons, heptagons, octagons, decagons, and dodecagons. They have also been struck with scalloped (wavy) edges, and with holes in the middle. Coins in the shape of polygons often have rounded edges or are Reuleaux polygons.

This article focuses on circulating coins; a number of non-circulating commemorative coins have been made in special shapes, including guitars, pyramids, and maps.[1]

Squares and diamonds[edit]

Indo-Greek coins were often square.

Many countries have struck square coins with rounded corners. Some of these, such as the Netherlands 5 cent coin of World War II and the Bangladesh 5 poisha coin, are oriented as a square, while others, such as the Netherlands Antilles 50 cent and the Jersey 1 pound coin, are oriented as a diamond.

Siege money, such as Klippe coins or the siege money of Newark, was often in the shape of a lozenge.

Pentagonal[edit]

The Mutawakkilite Kingdom of Yemen introduced pentagonal116 and ​18 rial coins in 1948.

Hexagonal[edit]

The Belgian Congo had a hexagonal 2 franc coin, and did the Kingdom of Egypt (2 piastres), and Burma (25 pyas). India used to have 3 paise and 20 paise coins that were hexagonal with rounded corners.

The 50 fils coin from the UAE is a Reuleaux heptagon.

Heptagonal[edit]

The Madagascar 10 ariary coin is seven-sided. The British twenty pence and fifty pence coins are heptagonal Reuleaux polygons, as is the United Arab Emirates 50 fils coin, the Barbados one dollar coin, and several coins from Botswana. Reuleaux polygons have constant width, which means the currency detectors in coin-operated machines do not need an extra mechanism to detect shape.[2]

Octaganal 2​12 milliemes coin from the Kingdom of Egypt.

Octagonal[edit]

The Chile 50 peso coin is eight-sided, as was the old Malta 25 cent coin, some California gold coins and one of the U.S. Panama–Pacific commemorative 50 dollar coins of 1915.

Nonagonal[edit]

The Tuvalu 50 cent coin has nine sides.

Britain used a dodecagonal threepence from 1937 to 1971.

Decagonal[edit]

Hong Kong had a ten-sided 5 dollar coin from 1976 to 1979, while the Philippines had a ten-sided two peso coin from 1983 to 1990.

Hendecagonal[edit]

The old Indian 2-rupee coin was eleven-sided, while the Canadian one dollar coin is an eleven-sided Reuleaux polygon.

Dodecagonal[edit]

Many countries have struck twelve-sided coins. Coins currently circulating include the British one pound coin; 50 cent coins from Australia, Fiji, and the Solomon Islands; the Tongan 50 seniti coin; and the Croatian 25 kuna coin.

The 20 koruna coin from the Czech Republic is tridecagonal.

Tridecagonal[edit]

The Czech 20 koruna coin has 13 sides.

Pentadecagonal[edit]

A 5 dirham commemorative coin from the UAE in 1981 had 15 sides, commemorating the 15th century of Hejira.

This 50 dirham coin from Libya has a scalloped edge with sixteen bumps.

Scalloped[edit]

Many countries have coins with scalloped (wavy) edges. These usually have twelve bumps (e.g. the Vanuatu 100 vatu or the Hong Kong 20 cents), but can have other numbers such as eight (the Swaziland 10 cents or the Ang Bagong Lipunan Philippine five centavo coin) or sixteen (the Libya 50 dirhams).

Holed[edit]

Often a round coin will have a central hole. In some countries this was to allow them to be strung together,[3] while other reasons include difficulty of counterfeiting and ability for visually impaired people to distinguish them from other coins.[4]

Chinese cash coins had a square hole, while many modern coins have a round hole. Examples include the Japan 5 yen coin and the Denmark 1 krone coin.

See also[edit]

References[edit]

  1. ^ Plautz, Jason (13 May 2013). "11 Unusually Shaped Coins". Mental Floss. Retrieved 1 July 2018.
  2. ^ Houston, Kevin (8 July 2011). "Curves of constant width – The 50p story". Retrieved 1 July 2018.
  3. ^ "Why Do Some Ancient Coins Have Holes In Them?". Retrieved 3 July 2018.
  4. ^ Gordenker, Alice (20 June 2006). "5 yen and 50 yen coins". The Japan Times. Retrieved 3 July 2018.

External links[edit]