From Greek 'Magnetis lithos' (Magnesian stone) — named after Magnesia, which also gave its name to magnesium.
A piece of iron or other material that has the property of attracting certain metals.
From Latin 'magnes' (lodestone, magnetic iron ore), from Greek 'magnēs lithos' (stone of Magnesia) — named after Magnesia, a district in ancient Thessaly (and another in Lydia) where lodestone deposits were famously found. The place name 'Magnesia' is pre-Greek, possibly from an ancient Anatolian or Aegean toponym whose deeper roots are uncertain. Greek natural philosophers including Thales of Miletus marvelled at the lodestone's invisible attractive force, making 'magnēs' one of the earliest technical words in Western scientific vocabulary. The Latin borrowing
The ancient Greek city of Magnesia gave its name to three different elements/substances: 'magnet' (from lodestone found nearby), 'magnesium' (isolated from magnesia alba), and 'manganese' (from a mineral also called magnesia) — three words, one city, three completely different materials.