Breaking a Mirror
Recorded English folk belief
This account does not specify seven years of bad luck. It records death and family ruin, so those meanings should not be merged into a single rule.
William Henderson, Notes on the Folk-Lore of the Northern Counties of England and the Borders, new edition (1879), Life and Death of Man; Sussex list of death omens, paragraph beginning “The following list of death omens”
A recorded Sussex belief that breaking a looking-glass foretells a death.