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Black Spots on Cent Business Strike Coinage 2000+

I just finished searching through a huge number of Lincoln cent rolls starting in about 1957 and what I found particularly interesting was the changes in quality of the coins as the years progressed. When the zinc plated cents were introduced, it's interesting that the die polish lines, so commonly found on the full copper cents, virtually disappeared. Then in 1992, the finish and quality seemed to take a big leap forward - all the zinc bubbles and plating errors were gone. From 1992 to about 1999 it seemed like the finish and strike of the cents were amazing. Then about 2000 it took a noticeable dip and from about 2000-2015 many of the business strike cents are covered, to a greater or lesser degree, in black spots. These aren't the carbon spots you see in coins pre-1960 - looks like they were part of a final rinse or something. Further, it's interesting that the coins in the sealed mint sets are fairly spot-free.

Has anyone ever published any information on what these black spots are caused by/what they are? Did the mint change procedure around 2000 and subject coins going into bags to an acid rinse or something while sparing the cents going into mint sets?

Makes it particularly difficult to find good non-satin business strike editions of 2007-2010 cents that aren't all spotted up.

Comments

  • Insider2Insider2 Posts: 14,452 ✭✭✭✭✭

    You've made a very interesting study. Thanks for posting. The majority of the ones I generally see are brownish-black and seem to have been liquefied at one time. IMO, the coins left the mint with the spots or something on them that caused them to develop later.

  • WaterSportWaterSport Posts: 6,705 ✭✭✭✭✭

    If I recall, a few years back this was a big subject on these forums. (mainly because no one could get a MS 66 Cent graded because of the spots LOL) But anyhow, it got PCGS attention and I believe they even went and made an appointment with the Director of the mint to find out just how the cents were being processed and what was the chemical wash causing the spots. It does not seem to be an issue any longer.

    WS

    Proud recipient of the coveted PCGS Forum "You Suck" Award Thursday July 19, 2007 11:33 PM and December 30th, 2011 at 8:50 PM.
  • rickoricko Posts: 98,724 ✭✭✭✭✭

    That issue was discussed here on several threads some years ago. I never did see a conclusion or identification of the black material. Much like milk spots on ASE's....just seems to be a problem that will not have an answer....although I feel certain the mint likely knows. Cheers, RickO

  • pmacpmac Posts: 3,189 ✭✭✭

    Poor choice of material for zincolns by the mint. I think that one cent coins should be made only with copper and only included in mint and proof sets. Electrolysis will render these coins useless well before their time, which has passed already.

    Paul

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