Complex sentence: Over the next few decades, the family became known for their global successes in mining and smelting (including the American Smelting and Refining Company) and eventually the family possessed one of the largest fortunes in the world.
Split into simpler sentences: Over the next few decades, the family became known for their global successes in mining and smelting, including the American Smelting and Refining Company. Eventually the family possessed one of the largest fortunes in the world.