means A naturally magnetized piece of the mineral magnetite that attracts iron, historically used as the first compasses; figuratively, anything that powerfully draws people or attention toward it.

from From Middle English 'lode,' meaning 'way' or 'course' (the same 'lode' that survives in 'lodestar,' the guiding star sailors steered by), plus 'stone' — so quite literally a 'way-stone' or 'leading stone.' That 'lode' descends from Old English 'lad,' meaning a journey or course, a cousin of 'lead' in the sense of guiding. Sailors prized these magnetic stones because, suspended on a thread or floated on water, they swung obediently toward north — a stone that knew the way.