I have a R15 block of 9 stamped Mich. So. & North'n Ind'a R.R. Co. and I'm looking for some opinions.

First, the ninth stamp in the block has some inking issues with the "S" on CENTS. Is it just an inking flaw?

Second, need an opinion on a blue fiber. Out of the block there was only a single fiber. Could the block be silk paper?


Thanks ya'll.