Note 2676 — BOOK XXXVI. THE NATURAL HISTORY OF STONES.
John Bostock translation
It was the belief of the Duke of Noya Caraffa, that this stone was identical with Tourmaline: but, as Beckmann says, tourmaline, when heated, first attracts iron, and then repels it. Hist. Inv. Vol. I. pp. 87, 88. Bohn’s Edition. Ajasson is of opinion that the Theamedes was neither more nor less than the ordinary loadstone, with the negative pole presented, by designing persons, towards another magnet.