This is the second installment in a two-part series about the business of coal mining.

Read the first article: Why is it so profitable for coal mining companies?

The first article covered why coal mining is such a profitable business.

But while the coal industry is widely considered to be a huge business, many of the mines in the United States are small, farmed-out operations, often with few workers.

And it is often a challenge for companies to get the workforce to work during peak times.

It also means that coal companies have to pay high salaries.

That is one of the reasons why the coal mining industry in the U.S. is growing at such a rate, and that it is attracting investors to join the industry.

“The coal industry has always been very dependent on mining,” said David Shaffer, a professor of public policy at Harvard Business School.

“There are very few mining companies that can compete with the mining industry.”

Shaffer said that when the boom years came around, coal companies had to look for ways to diversify their revenue streams.

“They had to do a lot of things that were going to hurt them,” he said.

“Those things were not the most profitable thing they could do.”

Shafer pointed to coal mining as an example of a company that took advantage of the economic crisis.

The U.K.-based company, which makes mining equipment, invested heavily in technology that would allow the company to extract more coal during the boom.

It even went so far as to build a coal-to-gas pipeline to bring more gas to the U