Interesting Toning pattern on there Austrian Shillings

Trooper

I know these are foreign, but I'm just posting them to show the toning that has taken place over the years. I just recieved these from my Aunt. They were purchased in Jan. 1983 from Blanchard & Co. I have the original reciept. This is probably the first time they were opened in many many years. Her boss used to by these things from Blanchard and give them to her. Sort of like, when you retire sell them....
The coins are dated in the 1975 to 79 range, many have an Olympic theme.
I have no idea if they are silver or not or what they are worth. I did take one out and the rev was untoned......It did read Hundert Schilling on the edge...

Here's a Blue velvet holder with Austian Shillings. Only the corner coins have any major toning on them. The bottom row shows about 1/4 inch of toning, but it's light. the rest are non-toned.

Why only the corners show the major toning?

Thanks
Tom

Gonfunko

Maybe the felt is glued down in the corners and is off-gassing to those coins only?