The Irish centre back was replaced late in the 1-0 defeat to Manchester City on Sunday, and will now undergo an operation on his right clavicle.
Ciaran Clark has also picked up a knee injury, and Villa Park boss Alex McLeish has wished the duo a speedy recovery.
“We’re gutted to be losing the big man,” the Scottish coach told the club’s official website.
“He was trying to get us back in the game when he made a tremendous leap but, unfortunately, he landed badly on his shoulder and fractured the collarbone.
“He is a stalwart defender and has been that for the past dozen years or so in the Barclays Premier League.
“It’s not good for us to be without such a top player and a defender of his massive experience.
“We wish Richard a speedy recovery and Ciaran, too, from his knee injury. We will look now for someone else to step up to the mark,” he stated.
Meanwhile, the Midlands club will be glad to hear that Chris Herd has recovered from an ankle ligament injury that has seen him on the sidelines since December.
The Australian is hoping to be available for selection for Villa’s game against Wigan on February 25th, and spoke of his delight at returning to fitness.
“I’m relieved to be back fit and training with the team,” Herd said.
“I’ll be training as hard as I can over the next few weeks to try and work my back into the side.
“It’s been really frustrating but I’m glad to be back and I still plenty more games to look forward to this season,” he concluded.
By Gareth McKnight