A broadstruck error occurs when a coin is struck without the collar to form the rim and edge that is part of the shape of the coin. Coins can be broadstruck on either type one or type two planchets. When a coin is broadstruck the blank being fed into the collar will spread and distort outward as it is being struck because the collar isn't in the correct position to retain it.

This is the only known United States $20 Gold Piece that was broadstruck out of the collar. It expanded in size and has a plain edge. $20 Liberty gold pieces were only struck at the Denver Mint in 1906 and 1907. This is the only known broadstruck $20 Liberty gold piece from ANY U.S. Mint. It is possible that there was an issue properly setting up the dies and collar to correctly strike these gold coins since it was the first year of striking, creating this unique broadstruck mint error.