The incident occurred in Clifton, Greater Manchester, as the train was travelling at 70mph on Friday, February 4.
Ian Birch, who works for Northern at their base in Blackburn, was left with cuts to his face after the brick smashed the cab window.
Mr Birch brought the train to a halt safely and praised a doctor travelling on board who was able to administer immediate first aid.
Despite appeals for information from Northern and British Transport Police, no arrests have been made.
Mr Birch said: “I want the people who did this to see the impact of their actions.
“I could have been blinded or even killed.
“Someone knows who threw that brick and I urge them to come forward.”
Anyone with information can contact BTP by texting 61016 or calling 0800 40 50 40.
Crimestoppers can be contacted anonymously on 0800 555 111.