Stone
Small witchstone shards or snowstone fragments worn on the person — used as personal amplifiers, sympathy links, or emergency spell reservoirs.
Pocket Stones are the working-class cousins of witchstones: small shards of irionite or snowstone, cheap to produce in quantity, carried on the person by apprentices, household retainers, and city watchmen. They don't grant High Magi rank on their own — they're too small and uncleansed for the full bonding process — but they do provide a modest reserve of arcane power, a sympathy link to a named master stone, or an emergency spell-cache.
Sevendor's Bouleuterion distributes pocket stones to graduating apprentices, and Pentandra's Vorone household runs on them. In the Magelaw the City Watch of Vanador carries standardised pocket stones tuned to the tower network, so that any watchman can raise the alarm through the Mirror Array.