Authors:

The leading distinction in magnets is the sex, male and female, and the next great difference in them is the colour. Those of Magnesia, bordering on Macedonia, are of a reddish black; those of Breotia are more red than black; and the kind that is found in Troas is black, of the female sex, and consequently destitute of attractive power.

"The Natural History of Pliny".
The leading distinction in magnets is the sex, male and female, and the next great difference in them is the colour. Those of Magnesia, bordering on Macedonia, are of a reddish black; those of Breotia are more red than