In chapter 25 of the same book Pliny describes five varieties of " magnes lapis."
There have been many conjectures as to the meaning of the words " magnes lapis."
Ore endowed with this curious property was well known to the ancient Greeks and Romans, who, because it occurred plentifully in the district of Magnesia near the Aegean coast, gave it the name of magnes, or the Magnesian stone.
1632) and Athanasius Kircher (Magnes, Rome, 1643), and maps of the ocean and tidal currents by the latter in his Mundus subterraneus (1665).
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