10 kopecks 2015 Russia M, from circulation
M under the horse's hoof – is a Moscow mint mark
Article about 10 kopecks 2014 Lemonka
It all started in 2006, in 2006-2014 10 kopecks began to be minted from steel, and before that 1997-2006 they were minted from brass. In 2006, there was an intersection... that is, in 2006, coins were minted both from steel (with a smooth edge) and from brass (with a ribbed edge). Brass coins did not require any additional coating, because brass is well preserved and does not rust. Steel coins from 2006 to 2013 were all coated with tombac alloy, that is, it was plating - that is, coating the coin with a thin layer of tombac sheet, with this coating on the edge of the 10 kopeck coin 2006-2013 had two colors - metallic and yellow. But they decided to improve this coating. Therefore, experimental 10 kopecks of 2014 with a new coating "Lemonka" appeared - with a brass galvanic coating, such coins have a solid yellow color on the edge (without a strip of steel). At the same time, in 2014, the bulk of 10 kopecks with the old coating - plating with tombac alloy.
In 2015, almost all 10 kopecks are "Lemonka" (with a brass galvanic coating). And only a few found examples of 10 kopecks of 2015 - with the old plating of tombac alloy.
Tombac alloy on 10 kopecks: this is 90% brass and 10% zinc (approximately).
Plating on 10 kopecks: plating is not spraying, this is a sheet of tombac alloy placed on the coin. The sheet does not completely envelop the coin, so the edge is partially coated. Because of this, the plated coins have 2 colors on the edge. Their native color of steel and yellow - tombac.
Galvanization on 10 kopecks: this is when the coin is coated evenly over the entire surface (including the edge), with a layer of tombac. It can be compared to the fact that if the coin is painted with an aerosol can. Therefore, the edge is uniformly yellow - "Lemon".
It is noteworthy that on the website of the central bank in the description of the coins of regular minting of 10 kopecks it is written that in 2015 there were 2 types of coating (Lemon and normal). This is true, but in reality there is very little normal coating, such a coin is expensive. But about 2014 on the website of the central bank it is not written that there were 2 types of plating. Although in 2014 2 types of coating are widespread, normal and "Lemon" (in percentage terms, there are more normal coatings than "Lemon", therefore "Lemons" are more expensive).
Collectors collect circulation coins by year and mints. Ciculation coins cost's higher than it's nominal value, because In some region of Russia can be rare coins with particular year, in other region - other year. For collectors it is hard to be in all regions...That is why collectors buy them to make their collection full.