It’s hard to say without actually handling it, but I definitely would pick it up. I have grabbed many rocks in MN—central/north and that certainly has a look of chert, agate/chalcedony, etc…. That tanish/yellowish crust in pic 2 is on many pieces of chert and also on Lake Superior Agates I have. As I mentioned, I would have definitely picked it up and probably take the diamond saw blade and cut a test slab off an end. You will find lots of chert in various colors, including banded chert which gets confused for agate sometimes due to the many lines…as chert was basically the sea floor if I remember correctly.
I'm not sure if your close to a college, close to the U of M or can find one of the many rock groups throughout the state, especially metro and show it to them for their answer…. Pretty sure there were a couple rock/fossil shops in N St Paul there or Roseville you may be able to check with. Don’t miss those winters, thankfully I don’t have to worry about that!😬🌞 Good luck!
