Basal ground, but the flaking (knapping) is Kirk Culture--quadra-facial sharpened, not beveled as a Lost Lake--I'm classifying the piece as a Pulaski, related to the Kirks and Neuberger point types. If the material is unusual, it's Illinois Elco Flint--cousin of the Dover Flint from Kentucky, slight color difference, but geologically very similar (see DeRegnaucourt's Chert Types for more info on the flint). Length is at 3&1/2" by nearly 1&7/16", only 5/16" max thickness. Being a layer-type chert, blades could be made much thinner than splitting open a nodule of flint. The barbs are intact, but one does show Early Archaic rounding; tip shows work polish. The piece came from a Jackson county, Illinois, collection, but wasn't marked as being found in that county--could also be Union County where the collector had previously lived. Patina is excellent, color is better that the pics show, guaranteed authentic. Shipping is $6.00. Payment welcomed by check or money order, however I do not use paypal--Roy A.