Complex sentence: The word "fluorine" derives from the Latin stem of the main source mineral, fluorite, which was first mentioned in 1529 by Georgius Agricola, who described it as a flux--an additive that helps melt ores and slags during smelting.
Split into simpler sentences: The word "fluorine" derives from the Latin stem of the main source mineral, fluorite, which was first mentioned in 1529 by Georgius Agricola. He described fluorite as a flux--an additive that helps melt ores and slags during smelting.