Dictionary Definition
loadstone n : a permanent magnet consisting of
magnetite that possess polarity and has the power to attract as
well as to be attracted magnetically [syn: lodestone]
User Contributed Dictionary
English
Etymology
First attested from 1515, from Middle English lode guide + stone, was used as a guide tool by mariners. See also: lodestar.Synonyms
Related terms
Translations
a magnet
- Portuguese: ímã
- Russian: магнетит, магнитный железняк
Extensive Definition
Lodestone or loadstone refers to either:
- Magnetite, a magnetic mineral form of iron(II), iron(III) oxide Fe3O4, one of several iron oxides.
- A piece of intensely magnetic magnetite that was used as an early form of magnetic compass.
Iron, steel and ordinary magnetite are attracted
to a magnetic
field, including the Earth's
magnetic field. Only magnetite with a particular crystalline
structure, lodestone, can act as a natural magnet and attract
and magnetize iron. The name "magnet" comes from lodestones found
in a place called Magnesia.
In China, the earliest literary reference to
magnetism lies in a 4th century
BC book called Book of the Devil Valley Master (鬼谷子): "The
lodestone makes iron come
or it attracts it." The earliest mention of the attraction of a
needle appears in a work composed between 20 and 100 AD
(Louen-heng): "A lodestone attracts a needle." By the 12th century
the Chinese were known to use the lodestone compass for
navigation.