The aggregate industry in the United States mines and sells billions of metric tons of crushed rock, sand and gravel each year. There are thousands of companies that produce aggregate in the U.S. and operate in all 50 states.
Roughly 8000 mega tons of Coal are produced annually. 90% is hard coal and 10% is lignite. It takes a vast amount of industrial equipment to produce this volume. MMI helps maintain this equipment to help ensure safety.