The error is an "obverse struck through clad layer". Instead of striking on a blank causing an indent, this Connecticut state quarter is struck on a detached clad layer (from another quarter I believe), leaving a somewhere blurry image on the obverse side. I like this quarter, since the "struck through" is positioned pretty nicely, covering Washington's face. It is a great "companion coin" to my other struck through clad layer Susan B Anthony $1. Please post if you have a similar "struck through clad layer" error coin.