Struck trough errors
The mints are in effect coin factories made up of a lot of complex equipment. In addition to machinery and various equipment, many other things could break and get into the beating chamber during the minting process.
When the monetary press is in operation, it may happen that a foreign object is inserted inside the beating chamber as well as the planchet to be minted. This "object" could be any solid or liquid substance, such as grease, bolts, plastic, planchets, coins, fragments of other minted coins and many other things.
By way of example, when one of these objects is inserted into the beating chamber together with the planchet while the coin press is in operation, the latter will be minted through the object and therefore its shape will be visible in the incuse on compromised area, as well as the imprint of dies.
In this case, when the object remains attached to the coin after minting, it will fill the space that would otherwise be left blank and the error would be designated as "Struck trough object". One of the most important things in typing through foreign objects is whether the object minted together with the coin can be identified. Most of the time it is simple, but it can also be difficult as the objects hit along with the coin are distorted due to the strong pressure exerted by the monetary press. If the object involved cannot be determined, the coin that presents this kind of error falls into the generic category "Struck trough foreign object", ie the coin was minted through something that remains undetermined.
In these cases, the coin increases in interest and consequently also in value when the object is large and can be identified. By way of example, the coin increases in rarity and value in a directly proportional manner depending on the size of the area of the coin involved, as happens for all types of minting errors.
In summary, this category is so broad that you could create a collection dedicated exclusively to this sub-category of striking errors.