Объясните употребление или отсутствие артиклей

Объясните употребление или отсутствие артиклей. Предложения переведите
1. He works as a mining engineer.
2. In 2006, there were over 2,200 active mines, quarries, and offshore drilling sites on the continental land mass of the United Kingdom.
3. The United Kingdom is the fourth largest producer of natural gas in the world, after Russia, the United States, and Canada.
4. Diamonds are pure carbon and the hardest mineral of all.
5. The uranium mining area of Krasnokamensk is situated in Eastern Siberia.
6. Roman miners dug vertical shafts and horizontal galleries and adits.