The space rock plunged into Lake Chebarkul on February 15 leaving a 6m-wide hole in the ice. Scientists say the segment that was taken out is the largest fragment of the meteorite yet found.
More than 1,000 people were injured when the 10,000-tonne meteorite burned up over Central Russia breaking windows and rocking buildings.
The five-foot-long rock broke into at least three large pieces as it was lifted from the ground for weighing. Then, the scale broke after it surpassed the 1,255lb mark.
Dr. Caroline Smith, curator of meteorites at London's Natural History Museum, confirmed that the object was a meteorite given its fusion crusts and regmaglypts.
"Fusion crust forms as the meteoroid is travelling through the atmosphere as a fireball," she said.
"The outer surface gets so hot it melts the rock to form a dark, glassy surface crust which we term a fusion crust. Regmaglypts are the indentations, that look a bit like thumbprints, also seen on the surface of the meteorite."
Divers have already recovered more than a dozen rock pieces from Lake Chebarkul since the incident, but only four or five turned out to be real meteorites.