These Copper coins from the Portuguese Monarchy are very hard to find in high grades. This one was recently acquired at a local coin fair and even though it was not cheap I just could not let it pass. These types of low denomination coins were really circulating at the time within the economic environment and therefore are very hard to find in MS grades. NGC Pop 2/0
Quoting NCS info regarding Carbon-Spots The term "carbon spots" refers to tiny black concentrations of corrosion. Oftentimes these are so small as to escape notice by the naked eye, though they may be seen with low-power magnification. Also called "flyspecks" by some in the hobby, these spots are actually slightly raised from the surface of the coin, as the corrosion forms around some particle of organic matter, such as paper dust (often present with coin albums and cardboard "2x2" stapled holders) or human saliva deposited unknowingly by a numismatist during casual handling. Oxygen, humidity, and other atmospheric elements react with the debris to form a minute mound of corrosion around it, and this is called a carbon spot. Removal of the debris will usually stop the reaction, and thus worsening of the spot, then and there. This may be as simple as removing the offending particle. The resulting corrosion, however, will remain as an unsightly black speck that can range greatly in size from nearly microscopic to as much as a quarter-inch in diameter, depending on how much mass the contaminant possessed and how long the reaction was occurring. Most often carbon spots will form on the surface of copper or bronze coins. The highly reactive nature of copper as a metal will often lead to their formation, but US copper-nickel coins as well as other copper-nickel coins from around the world are also quite susceptible. Most nickel alloys used for United States coinage are a combination of 75% copper and only 25% nickel. This includes the three- and five-cent pieces made since 1865 and the outer layers of our current dimes, quarters and halves, as well as those of the dollars coined 1971–99. The thick cents dated 1856–64 included 88% copper to only 12% nickel and, given their greater copper content, have an even greater susceptibility to developing carbon spots.
Thank you very much for the detailed answer. It helped me understand how they are created and ways to prevent and ultimatley stop these corrosion spots. And as alwasys enjoy what remains of your day.
