Brown coal would then be added to keep the fire going.
The region is home to the world's largest known reserves of brown coal.
In the 1930s, large deposits of brown coal were discovered there.
Brown coal was mined in the town until the 1990s.
They also contain large deposits of brown coal and natural gas.
Pollution from brown coal, the country's other major power source, was acute.
In the 18th century, brown coal was still being mined, although yields were quite small.
And energy still comes largely from highly polluting brown coal.
The most important reason was the transportation of brown coal from the north Bohemian basin.
Major natural resources include diamonds, gold, and brown coal.