i personly think somone has tryed to clean it and got that colour (i might be wrong) and can you a close up of the first t in "trust" and a close up of that dot under "i" & "B" in liberty it looks like another d mint mark to me
well something has certanly happened to the t it looks more like a y and i dont know what happened to the chopped of r mabye someone eles might know
What you have there is the aluminium core of the coin coming through. "copper" pennies are now made with aluminium coated - clad with copper. If the coating is thin then the stretching that occurs during stamping may make the core bleed through. I dont know if it is a desirable or rare error or even an error at all. It can also happen from wear or chemicals eating away the copper. Your looks like the coating was thin or non existant in the lower (4 o'clock) edge
You're right about one thing - the copper has been worn away. But it's not aluminum underneath - it's zinc. The coin has suffered damage after leaving the Mint.
I stand corrected concerning the composition. but I do dissagree with the damage after the mint. Although many pennies are seen with the copper removed from the tops of the raised letters (obvious wear) this coin has the copper missing in a sweeping area just below the date. Kind of like when you used play-do as a kid, mixed in two colors, then used a the play-do press. you'd see that added color get smeared, just like this coin. Notice how the show-through ZINC is "smeared" radially from the center of the coin? Also the way it "hangs up" under the date and along the bottom edges of the numbers, this happens when the top coating is too thin and then the planchete is squeezed outward in the coin stamping process. The areas in liberty, I-G-W-T, and the rim are probably wear or damage.
