An error coin is a coin that was manufactured incorrectly by a mint. Many times called mint errors, error coins come in scores of "shapes, sizes and types." The sheer variety of minted errors adds excitement and uniqueness in collecting them. Welcome to Hard Asset Management Error coin section., The key source for exceptional Major Mint Errors. Hard Asset Management has the world’s largest and most comprehensive selection of United States major mint error coins for purchase. Please feel free to browse our inventory to see if we have what you are looking for, or email us your want list.