The term lodestone is derived from "leading stone'" -- hence its connection to magnetism. Also, in medieval times iron oxides were known in two forms: the masculine, magnes, and the feminine, magnesia. Early in the 18th century a salt was discovered that was presumably related to the magnetic substances, but it was white, not black; hence it was named magnesia alba. It contained a metal which Humphrey Davy called magnium, later known as magnesium.
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