They were both called "magnes" from their place of origin, but were considered to differ in sex. The male "magnes" attracted iron, and was the iron ore now known as lodestone or magnetite, and which probably gave us the term magnet. The female "magnes" ore did not attract iron, but was used to decolorize glass. This female "magnes" was later called "magnesia", known now in modern times as pyrolusite or manganese dioxide. Neither this mineral nor elemental manganese is magnetic. In the 16th century, manganese dioxide was called "manganesum" (note the two Ns instead of one) by glassmakers, possibly as a corruption and concatenation of two words, since alchemists and glassmakers eventually had to differentiate a "magnesia nigra" (the black ore) from "magnesia alba" (a white ore, also from Magnesia, also useful in glassmaking). Michele Mercati called magnesia nigra "manganesa", and finally the metal isolated from it became known as "manganese" (German: "Mangan"). The name "magnesia" eventually was then used to refer only to the white magnesia alba (magnesium oxide), which provided the name magnesium for the free element when it was isolated much later.