Quarter Color? - Coin Community Forum

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Author	Replies: 6 / Views: 1,174
ksyim Valued Member United States 56 Posts	Posted 06/05/2009 1:14 pm I just found out that quarter is made of mainly Cu (>90%) with some Ni. My perception is that Cu is always red. How can Quarter coin be so white? Ni addition is such a powerful? How much Ni is need to make Cu alloy completely white color? I know, It's not important for our hobby. but, I'm just curious because I'm engineer. Any metallurgy person here to explain it? ^^ Report this Post to the Staff

steve199 Pillar of the Community United States 1882 Posts	Posted 06/05/2009 1:51 pm Quote: I know, It's not important for our hobby. Sure it is important! The coin is in layers. The center is 100% copper. The outer layer is 75% coppper, 25% nickel. Report this Post to the Staff
biokemist6 Bedrock of the Community United States 12437 Posts	Posted 06/05/2009 1:53 pm The 90% figure is a bit misleading due to the construction of a clad coin. You have three layers- the outer layers are 75% Cu 25% Ni(same as a five cent coin aka nickel) bonded to an inner core of pure copper. I am not sure how much nickel it takes to make a metal white but look at 1857-1864 cents- they are 88% Cu 12% Ni and are significantly "whiter" than a regular bronze cent. I found an interesting graph on Wikipedia regarding the color of gold and silver alloyed with copper, it should help shed a bit more light on the subject- Report this Post to the Staff
ErrorCoins222 Pillar of the Community United States 1699 Posts	Posted 06/05/2009 5:00 pm Cant you see the copper layer from the edge of the coin? And I think when it is completely "silver" on the edge, it could be a silver quarter. Report this Post to the Staff
ksyim Valued Member United States 56 Posts	Posted 06/05/2009 5:25 pm Wow... it's cool. You guys should have a degree in metallurgy! by the way, quarter clad has two layers or more? biokemist6 mentioned 3 layers? how come? Report this Post to the Staff
steve199 Pillar of the Community United States 1882 Posts	Posted 06/05/2009 5:50 pm 3 layers, like an Oreo cookie. Report this Post to the Staff
ksyim Valued Member United States 56 Posts	Posted 06/05/2009 6:35 pm I see. it's like Oreo cookie. I'm looking at one quarter from my pocket. yes. I can see reddish color from the edge. then, Anybody knows the spec of thickness ratio? I love technical discussion like this! Report this Post to the Staff
	Replies: 6 / Views: 1,174

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