Despite gold's price slump, strong copper and iron ore prices lifted MINING.COM's ranking of the world's 50 most valuable miners to a new record high of $1.35 trillion.
This year seasonal factors have limited output of renewables, including hydro electricity, which are weather dependent, helping coal's share to rebound.
Scientists say coal ash from the Punta Catalina power plant revealed high concentrations of arsenic, selenium and other potentially harmful heavy metals.