Memory stones were part of an ancient tradition in the Protectorate of Grayson, dating from the early exploration of the Yeltsin's Star System.
The survivors of an asteroid mining operation would carry a small piece of unrefined asteroid ore for six days, meditating on the debt owed to those who died in space, and praying for them. On the seventh day, the day the Tester rested, the stones were laid to rest by being launched into a trajectory that carried them into Yeltsin's Star.
Masadan agents blackmailed Samuel Mueller, Steadholder Mueller, into giving Queen Elizabeth III and Prime Minister Cromarty memory stones with homing devices to allow missiles to passively home in on their ships. However, thanks to Honor Harrington, Operation Hassan was only successful in killing Cromarty, not the queen. (HH9)