Editing Penny (United States coin) (section)

==History of composition==
The composition of the penny has varied over time:<ref>{{Cite web |date=September 20, 2016 |title=Coin Specifications |url=https://www.usmint.gov/learn/coin-and-medal-programs/coin-specifications |url-status=live |archive-url=https://web.archive.org/web/20220506205342/https://www.usmint.gov/learn/coin-and-medal-programs/coin-specifications |archive-date=May 6, 2022 |access-date=March 23, 2019}}</ref><ref>{{Cite web |last=U.S. Mint |date=September 3, 2019 |title=Coin Production |url=https://www.usmint.gov/learn/history/coin-production#composition |url-status=live |archive-url=https://web.archive.org/web/20201218023158/https://www.usmint.gov/learn/history/coin-production#composition |archive-date=December 18, 2020 |access-date=December 20, 2020}}</ref>
{| class="wikitable"

|- style="text-align: left;"

! Years !! Material !! Weight<br />(grains) !! Weight<br />(grams)
|-
| 1793–1795 || ~100% [[copper]] || 208 grains || 13.48
|-
| 1795–1857 || ~100% copper || 168 grains || 10.89
|-
| 1856–1864 || 88% copper, 12% [[nickel]] (also known as [[nickel silver|NS-12]]) || 72 grains || 4.67
|-
| 1864–1942 || [[bronze]] (95% copper, 5% tin and zinc) || 48 grains || 3.11
|-
| 1943 || zinc-coated steel (also known as [[1943 steel cent]]) || 42 grains || 2.72
|-
| 1944–1946 ||[[gilding metal]] (95% copper, 5% zinc) || 48 grains || 3.11
|-
| 1947–1962 || bronze (95% copper, 5% tin and zinc) || 48 grains || 3.11
|-
| 1962 – September 1982 || gilding metal (95% copper, 5% zinc) || 48 grains || 3.11
|-
| October 1982 – present || copper-plated zinc (97.5% zinc, 2.5% copper) || 38.6 grains || 2.5
|}

The [[isotope]] composition of early coins spanning the period 1828 to 1843 reflects the copper from [[Mining in Cornwall|Cornish]] ores from England, while coins after 1850 reflect the [[Keweenaw Peninsula]], Michigan ores, a finding consistent with historical records.<ref>{{Cite journal |last=Mathur |first=R |year=2009 |title=The history of the United States cent revealed through copper isotope fractionation |journal=Journal of Archaeological Science |volume=36 |issue=2 |pages=430–433 |doi=10.1016/j.jas.2008.09.029|bibcode=2009JArSc..36..430M }}</ref>

In 1943, at the peak of [[World War II]], [[1943 steel cent|zinc-coated steel cents]] were made for a short time because of war demands for copper. A few copper cents from 1943 were produced from 1942 [[planchet]]s remaining in the bins. Similarly, some 1944 steel cents have been confirmed. From 1944 to 1946, salvaged [[ammunition]] shells made their way into the minting process, and it was not uncommon to see coins featuring streaks of [[brass]] or having a considerably darker finish than other issues.

During the early 1970s, the price of copper rose to the point where the cent contained almost one cent's worth of copper. This led the Mint to test alternative metals, including [[aluminum]] and [[bronze]]-clad [[steel]]. Aluminum was chosen, and over 1.5 million samples of the [[1974 aluminum cent]] were struck before ultimately being rejected.

The cent's composition was changed in 1982 because the value of the copper in the coin started to rise above one cent.<ref>{{Cite web |last=Meridith |first=Stephanie |date=February 1, 2022 |title=Historic Coin Production |url=https://www.usmint.gov/learn/history/historic-coin-production |url-status=live |archive-url=https://web.archive.org/web/20230618100733/https://www.usmint.gov/learn/history/historic-coin-production |archive-date=June 18, 2023 |access-date=September 20, 2023 |website=United States Mint }}</ref> Some 1982 cents used the 97.5% zinc composition, while others used the 95% copper composition. United States cents minted after 1982 have been zinc with copper plating. The bronze and copper cents can be distinguished from the newer zinc cents by dropping the coins on a solid surface, or by flipping them in the air with your thumb. The predominantly zinc coins make a lower-pitched "clunk" when hitting the surface, and make no sound when flipped in the air; while the copper coins produce a higher-pitched ringing sound.<ref name="ring">{{Cite web |title=Is my Penny a Copper, or a Zinc Cent? |url=http://coins.about.com/od/uscoins/f/copper_to_zinc.htm |url-status=dead |archive-url=https://web.archive.org/web/20110707074834/http://coins.about.com/od/uscoins/f/copper_to_zinc.htm |archive-date=July 7, 2011 |access-date=June 16, 2008}}</ref> In addition, a full 50-cent roll of pre-1982/3 coins weighs {{convert|5.4|oz|g|abbr=on}} compared to a post-1982–83 roll which weighs {{convert|4.4|oz|g|abbr=on}}.