Striated, Striation. Parallel incised lines or stripes; bands of very tiny adjacent channels on the surface of a numismatic piece. Natural striation is caused by metal flow on the face of a struck piece and results in mint luster. A striated surface can also be created by design as a background texture. Striated lines in a die (as file marks) would form raised striated lines on a piece struck from that die. According to numismatic writer Walter Breen these appear on some 20th century U.S. coins (as the 1921 Peace dollar and some commemoratives).

References:

NC8 {1988} Breen.