Plains, Pennsylvania — In three weeks, when the first visitors walk through the main entrance of the new casino at Mohegan Sun at Pocono Downs, they will pass a sculpture that starts as a hunk of coal at its base. Slowly, as it spins toward the ceiling, fist-sized black chunks morph into clear rocks and finally into polished diamonds. When the USD 208 million expansion opens July 17, it will reflect the Pennsylvania coal country where it sits and how the Mohegan Tribal Gaming Authority...