1978-D Washington Quarter 25C Denver Business Strike in Fine Condition KM#164 Filled D variety- completely filled. Due to the aging minting equipment and dies used in Denver during 1979, there are recognizable errors are heavily sought after by numismatists: Filled Mint Mark: The Denver "D" is sometimes distorted or filled in, resulting from worn dies or die chips. These errors can fetch anywhere from $15 to $300+ on the secondary market depending on the severity.