Random White Line. Error? Which Kind?

to CCF. I can't help with your question, but I am sure other members can.
John1

Hello and welcome.

I believe there are different causes here.

In the first pic, we can see that the "white line" is perfectly parallel to the "grain" of the metal. In which case, the "line" is caused by an improperly mixed alloy, leaving a blob of metal of slightly different composition which then got stretched out into a line as the metal was rolled and stretched prior to the coin blank being punched out of the strip of metal. It isn't really an "error", as you could not tell the flaw was there when the coin was brand new; it is only as the coin has aged and the different parts of the coin with different compositions have oxidized differently that you can tell. In bronze coins, such an effect is called "wood-grain toning"; I don't know what you'd call it on an aluminium coin.

The effect seen in other three pictures is caused by something different. Here, it seems that something corrosive - perhaps the corner of a plastic coin holder or album page made of PVC or some other plastic that corrodes coins - has sat on the coin for a long time and caused that particular pattern of corrosion. It is not a mint error.

Is the "line" above or below the surface?
John1