Coal

a black or dark-brown combustible mineral substance consisting of carbonized vegetable matter, used as a fuel.
Compare anthracite, bituminous coal, lignite.
a piece of glowing, charred, or burned wood or other combustible substance.
charcoal (def 1).
to burn to coal or charcoal.
to provide with coal.
to take in coal for fuel.
heap coals of fire on someone’s head, to repay evil with good in order to make one’s enemy repent.
rake / haul / drag / call / take over the coals, to reprimand; scold:
They were raked over the coals for turning out slipshod work.
Contemporary Examples

GOP’s Biggest 2016 Problem: Clinton’s Numbers Among White Voters Lloyd Green June 8, 2014
Thatcher’s Economic Legacy Megan McArdle April 7, 2013
Obama’s New Emissions Rules Will Yank the Climate Change Debate Back Into Reality Sally Kohn June 1, 2014
The Bond Market Goes Green The Daily Beast May 26, 2014
How Drugs Ruined This Small Town David Frum April 28, 2013

Historical Examples

World’s War Events, Vol. I Various
Woman’s Institute Library of Cookery, Vol. 5 Woman’s Institute of Domestic Arts and Sciences
The Land of Tomorrow William B Stephenson, Jr.
The Field of Ice Jules Verne
Custom and Myth Andrew Lang

noun

a combustible compact black or dark-brown carbonaceous rock formed from compaction of layers of partially decomposed vegetation: a fuel and a source of coke, coal gas, and coal tar See also anthracite, bituminous coal, lignite, peat1
(as modifier): coal cellar, coal merchant, coal mine, coal dust

one or more lumps of coal
short for charcoal
coals to Newcastle, something supplied where it is already plentiful
haul someone over the coals, to reprimand someone
verb
to take in, provide with, or turn into coal
n.
coal
(kōl)
A dark-brown to black solid substance formed from the compaction and hardening of fossilized plant parts in the presence of water and in the absence of air. Carbonaceous material accounts for more than 50 percent of coal’s weight and more than 70 percent of its volume. Coal is widely used as a fuel, and its combustion products are used as raw material for a variety of products including cement, asphalt, wallboard and plastics. See more at anthracite, bituminous coal, lignite.

see:

carry coals to Newcastle
rake over the coals