Three thuringians and a ?

Well i have a couple of pics here of my thuringians 2 lighter stones that are beautiful to hone with and a couple of darker stones that i thought were the same, but in the light of day not so, the stone numbered no 2 i got from Germany still has saw markes on the sides its a really nice stone.
Number one stone i just scored from an old barber's estate and cleaned and laped excitedly, i was thinking its the same stone as the german one, exact size 204mm long and 45-50mm wide and both stones have a weight to them for there size. The new one performs great improved the edge off a coti, but i really had trouble working up a slurry with a rub stone nothing much at all so the stone is harder than the german one. In the light you can see from the pics the difference in them so any ideas in the no 1 new stone would be appreciated cheers .
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Where is the envy emoticon???