The manganese brass in the coin is part of the outer layer. Like any brass, its color will eventually become darker, giving these coins an antique finish. As the coins are handled frequently, the darker "patina" may wear off the high points of the coin, leaving golden-colored highlights that accent the darker background around the border, lettering and other less exposed areas. The brighter, brass highlights, in contrast with the darker background, accentuate the profile and add a dimension of depth to the depiction of Sacagawea and her child.