Coal mining had been an important industry in the past.

Coal mining was an important industry in the area since the 15th century.

Since 1890, coal mining has also been a political and social issue.

The major work of the area used to be coal mining.

Coal mining would become the main industry in this area.

Coal mining is central to the economy of the region.

The coal mining goes on right in the middle of a huge population.

From the first half of 19th century coal mining developed.

This time, he does not see a future in coal mining.

In the 20th century it became a center for coal mining.