The surface of your artifact appears to be patinated to a lighter color and if so it could be somewhat difficult to ID. The remaining cortex on your example suggests it was in nodular form.
Here are two unpatinated samples of Georgetown (Edwards).
If you were to shine a bright light through it, what color would you see? I also agree that it has been heavily patinated. Personaly, I've seen that type of patinization mostly on "Rootbeer" flint. Heres as Scotty I found a few years ago that is so heavily patinated you have to hold it to the light to see that it was once an nice translucent brown. BTW, nice artifact you have there regardless of material.
No translucency on this one to speak of. Only the very thinnest edges let light through at all. The color in hand is just about the color I see on my screen looking at the picture. Kind of the shade of coffee with not enough milk in it to do much more than lighten it to a greyish shade, with white splotches.
Think you could ID it if I sent it to you to examine ?
Uniface, the piece that you show is more than likely Edwards flint...the heavy patina is the same as some I have from the Austin area...by the way, nice piece...You might see if you can get in touch with NeoGeo, he is from that area and has a lot of nice examples of that flint...OG