Thanks Brad, I do appreciate that is the case.
Clearly it is not an Escher, otherwise it would have said so on the label instead of 'Made In Germany' so a comparison of Escher marks is not necessary. It probably is a slate from a similar or even the exact same strata that Escher & Co cut theirs from - geological strata/deposits/layers do tend to be quite huge, after all! The name of the company that quarried it, cut it up and marketed it doesn't really matter IMO - how the product hones is, though.
The way I read Sham's query was as to whether the label was original as it is in such good condition. It does appear to be in excellent condition. I agree with ChrisL that you would have to examine the actual label to see if it is a modern reproduction - you don't have to be an Escher expert to do that.
Regards,
Neil