A man approached her at about 11:30am and ran off with her bag, which was later found dumped in Fecitt Brow.
The offender is described as being white and in his twenties with a shaved head wearing a white t-shirt.
Detective Sergeant Mark Saunders from Blackburn CID said, “I would appeal to anyone who was in the area at the time and witnessed the incident to come forward and contact the police.
“Although the victim wasn’t hurt during the incident she has been left traumatised following her ordeal. The person responsible needs to be caught and I would ask the public to come forward and help us if they can.”
Anyone with information is asked to call Blackburn CID on 101.