Coal
It is by no means certain that the Hebrews were acquainted with mineral coal, although it is found in Syria. Their common fuel was dried dung of animals and wood charcoal. Two different words are found in Hebrew to denote coal, both occurring in Prov. 26:21, "As coal [Heb. peham; i.e., "black coal"] is to burning coal [Heb. gehalim]." The latter of these words is used in Job 41:21; Prov. 6:28; Isa. 44:19. The words "live coal" in Isa. 6:6 are more correctly "glowing stone." In Lam. 4:8 the expression "blacker than a coal" is literally rendered in the margin of the Revised Version "darker than blackness." "Coals of fire" (2 Sam. 22:9, 13; Ps. 18:8, 12, 13, etc.) is an expression used metaphorically for lightnings proceeding from God. A false tongue is compared to "coals of juniper" (Ps. 120:4; James 3:6). "Heaping coals of fire on the head" symbolizes overcoming evil with good. The words of Paul (Rom. 12:20) are equivalent to saying, "By charity and kindness thou shalt soften down his enmity as surely as heaping coals on the fire fuses the metal in the crucible."