A coal mine is a place where coal is mined for its energy content and used to generate electricity. In a dream, a coal mine could be representative of a person asking God for a greater zeal or one who is searching in a dark place and being lost.
Positive: Dreaming of being in a coal mine could show one being in a place of searching for deeper revelation of God. This could show a person desiring to have more zeal for God.
Negative: Dreaming of a coal mine could indicate that one is in a depressed or low place and needs to seek God.
(2 Chronicles 15:2; 1 Corinthians 2:10; Isaiah 41:10).