I found this blade near a spring outside of Angela, MT. The guy I was with said it is made of knife river flint. There is a pretty heavy white patina on it, it appears to have been outside for a long time. Only flaw on it is a slight chip out of the side that I think happened when I was freeing it from the clay it was fused to.
Very thin, great flaking. But I don't know anything about the artifact types in that part of the country.
The patina on the back side of that point really jumps out at you. MT is rich in articulate and lanceolate point types so typing your piece would be a process of elimination. That slightly convex base (if its ground) and the flaking indicates Milnesand. A point can accumulate a lot of mineralization during 11,000 years.
It is a nice piece and I believe it is Paleo.
I did so some trout fishing while there (amazing), but that was in Bozeman, and the artifcats I found were in the Eastern part of the state. That is a tough place to hunt for points...lots of grassy plains, and while you find a TON of chips on top of the ridges, sheepherders in the 1930s with lots of time on their hands camping on the ridges tended to clean most everything out.
I would also recommend hitting the Range Rider's Museum in Miles City. Shortly before I visited it, a pair of elderly local brothers bequeathed their entire arrowhead collection to the museum. They had spent their entire lives working outdoors and had built a massive collection since childhood. They had to erect an entire new building to house the artifacts...unreal assortment of point types and material. I'll post some picas later tonight.