NEW YORK -- Giants outfield prospect Chuckie Jones was suspended for 50 games on Thursday after testing positive for a banned substance.

The Office of the Commissioner of Baseball said Jones received a 50-game suspension without pay following a second positive test for a drug of abuse in violation of the Minor League Drug Prevention and Treatment Program. The suspension is effective immediately.

Jones, 22, was San Francisco's seventh-round pick in the 2010 Draft out of Boonville High School in Missouri. He spent all of last season with Class A Advanced San Jose, where he hit .256 with 15 homers, 66 RBIs and 17 stolen bases in 131 games. The 6-foot-3 right fielder was again slated to begin the season on Thursday with San Jose.

Jones made his Minor League debut in 2010 with the Rookie-level Arizona League Giants and has worked his way through the system with stops at Salem-Keizer and Class A Augusta. In 436 career games, he's batted .238 with 39 homers, 181 RBIs, 43 steals and a .323 on-base percentage over 1,503 at-bats.

Players are typically issued a warning following a first positive test for a drug of abuse and a suspension for a second offense. Substances considered "drugs of abuse" by Major League Baseball include cocaine, marijuana, heroin, LSD, ecstasy and other opiates.

Jones is the 45th player, fourth Giants prospect and second San Jose batter to be suspended this year for violating the Minor League drug program.