The Weasley family clock is an Enchantment.
It tracked the location of all members of the Prewett line through the Albion family magics. When Molly's brothers were murdered by you-know-who the clock became matrilineal and passed on to her.
[ v ]Enchantments
|Dynamic space expansion · Earpiece communication mirrors · Granger magic trunk engine · Magical space folding · Weasley family clock|
[ v ]Human magic
|Wand based||Alchemy · Charms · Duelling · Transfiguration · Wand lore|
|Wandless||Enchantments · Herbology · Necromancy · Potions · Rituals|
|Mixed||Divination · Healing · Magical theory · Mind magic|