Complex sentence: He became a principal in Standard Coal Co., developing mines in Tennessee and West Virginia subsequently establishing Sapphire Trading Company which reopened the Yogo Sapphire Mine in Montana and the Noble Metals Mine Operation in Southern California and Nevada.
Split into simpler sentences: He became a principal in Standard Coal Co., developing mines in Tennessee and West Virginia. Subsequently he established "Sapphire Trading Company" which reopened the Yogo Sapphire Mine in Montana and the Noble Metals Mine Operation in Southern California and Nevada.