Rolf William Johnson, 19, is accused of throwing the 3-foot mirror from the 12th-floor of a CU dorm, which struck Joshua Moran, 20, in the head Friday, the Boulder (Colo.) Daily Camera reported.
Moran reportedly left Boulder Community Hospital Friday after being treated for injuries.
"His injuries could have been much more tragic than they were. It's easy to understand how it could have been a fatality," police Cmdr. Brad Wiesley said.
Johnson was held at Boulder County Jail on a bond of $5,000 and is faced with charges of second and third-degree assault and reckless endangerment, the newspaper said. He was scheduled to appear in court Monday. The CU Office of Judicial Affairs reportedly is responsible for deciding whether he will be punished by the school.