The upwelling of this element intermittently reduced the effect of free radical damage to early cyanobacteria according to Preston Cloud’s theory for the formation of structures named for this element. Stony (15[1])meteorites (15[1])are contrasted with meteorites named for this element. (15[1]-5[2])The existence of (15[1])the Great (15[1])Oxygenation Event was (-5[1])predicted by the disappearance of (*) “banded formations” (10[1])named for this element after the Archaean (10[1])Eon. The presence of titanium and this element in (10[1])corundum results in sapphire’s blue hue. The discontinuous branch of Bowen’s (10[1])reaction series is composed of mafic minerals which are named for being rich in magnesium and this element. Hematite and magnetite are the primary ores of, for 10 points, what metal which alloys with carbon (10[1])to form steel? (10[1])■END■ (10[1])