Coal in the Bible is a translation of several Hebrew and Greek words. It refers mainly to charcoal made from burning wood. The mineral coal that is mined from the ground is not found in Palestine (the Holy Land). People used glowing embers from wood fires for several purposes:
For heating homes (Isaiah 47:14; John 18:18)
For cooking food (Isaiah 44:19; John 21:9)
By blacksmiths for metalworking (Isaiah 54:16)
In religious ceremonies, where coals from the altar had special uses (Leviticus 16:12; Isaiah 6:6–7)
The Bible also uses coal as a symbol in many ways. It represents:
The infinite brightness and glory of God (2 Samuel 22:9, 13)
God's revelation (Psalm 18:8)
Heavenly creatures associated with the throne of God (Ezekiel 1:13; 10:2).
In other places, glowing coals represent:
Life itself (2 Samuel 14:7)
The hot breath of a huge beast (Job 41:21)
The danger of being harmed by sexual sin (Proverbs 6:28)