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As you see on the non-grey side of your find, the exterior "skin" of chert-nodules tends to deteriorate by weathering, and will no longer scratch glass. You'd need a "fresh" piece from the nodule's interior to do the scratch test on glass. I learned that when I was a rockhound and a Geology Minor back in college.
Remember, I said "looks like." That phrase means it resembles a particular object or material, but it might not actually be. That being said, I still think it looks like a chert-nodule. I suggest you take both of your finds to the nearest college's Geology Department.