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Related to coal: charcoal, petroleum

canary in a coal mine

Something or someone who, due to sensitivity to his, her, or its surroundings, acts as an indicator and early warning of possible adverse conditions or danger. Refers to the former practice of taking caged canaries into coal mines. The birds would die if methane gas became present and thereby alert miners to the danger. Wildlife in disaster movies assumes the role of the canary in a coal mine, fleeing the scene when catastrophe is imminent. Unaware that he had been given the test drug, John was used as a canary in a coal mine to see its effects on the human mind.
See also: canary, coal, mine

haul (someone) over the coals

To scold, reprimand, or reprove someone severely for an error or mistake. I was hauled over the coals by my boss last week for messing up the accounting software. I know Mary messed up, but don't haul her over the coals too hard for it.
See also: coal, haul

rake over old coals

To revisit, dredge up, or talk about something that happened in the past, especially that which is unpleasant. Primarily heard in UK. Now, now, there's no need to rake over old coals, that disagreement happened a long time ago.
See also: coal, old, rake

blow the coals

To turn a minor issue into a major source of conflict. Likened to coaxing a smoldering flame into a fire by literally blowing on hot coals. Stop trying to blow the coals! There is no tension between Jen and me—you're imagining it! A: "What went wrong last night?" B: "Well, you know Sue, she just kept blowing the coals until everybody was in an all-out fight."
See also: blow, coal

carry coals

To allow oneself to be mocked or humiliated. You shut your mouth right now! I refuse to carry coals just because you're angry about work!
See also: carry, coal

heap coals of fire on (one's) head

To make a special effort to induce feelings of guilt or remorse in another person. Why are you citing all these examples of times I wronged you? Why are you heaping coals of fire on my head?
See also: coal, fire, head, heap, of, on

at the coalface

Actively doing a certain job. Primarily heard in UK, Australia. These reports are just speculation—they didn't consult anyone actually at the coalface. I earned my retirement after 30 years at the coalface.

carry coals to Newcastle

Prov. to do something unnecessary; to do something that is redundant or duplicative. (Newcastle is an English town from which coal was shipped to other parts of England.) Mr. Smith is so rich he doesn't need any more money. To give him a gift certificate is like carrying coals to Newcastle.
See also: carry, coal, Newcastle

rake someone over the coals

 and haul someone over the coals
Fig. to give someone a severe scolding. My mother hauled me over the coals for coming in late last night. The manager raked me over the coals for being late again.
See also: coal, rake

at the coalface

  (British & Australian)
someone who is at the coalface is doing the work involved in a job, not talking about it, planning it, or controlling it You sit in your office looking at consultants' reports, but it's the men and women at the coalface who really understand the business.

carry/take coals to Newcastle

to take something to a place or a person that has a lot of that thing already
Usage notes: Newcastle is a town in Northern England which is in an area where a lot of coal was produced.
Exporting pine to Scandinavia is a bit like carrying coals to Newcastle.
See also: carry, coal, Newcastle

drag/haul somebody over the coals

to speak angrily to someone because they have done something wrong If I make a spelling mistake, I get hauled over the coals by my boss. (often + for ) They dragged her over the coals for being late with her assignment.
See rake over the coals
See also: coal, drag

rake over the coals

to talk about unpleasant things from the past that other people would prefer not to talk about (usually in continuous tenses) There's no point in raking over the coals - all that happened twenty years ago, and there's nothing we can do about it now.
See also: coal, rake

black as night

Also, black as coal or pitch . Totally black; also, very dark. For example, The well was black as night, or She had eyes that were black as coal. These similes have survived while others-black as ink, a raven, thunder, hell, the devil, my hat, the minister's coat, the ace of spades-are seldom if ever heard today. Of the current objects of comparison, pitch may be the oldest, so used in Homer's Iliad (c. 850 b.c.), and coal is mentioned in a Saxon manuscript from a.d. 1000. John Milton used black as night in Paradise Lost (1667).
See also: black, night

carry coals to Newcastle

Do or bring something superfluous or unnecessary, as in Running the sprinkler while it's raining, that's carrying coals to Newcastle. This metaphor was already well known in the mid-1500s, when Newcastle-upon-Tyne had been a major coal-mining center for 400 years. It is heard less often today but is not yet obsolete.
See also: carry, coal, Newcastle

pour on the coal

Speed up, as in They keep passing us so pour on the coal, Mom! or We can get this issue of the paper out on time if we pour on the coal. This slangy expression originated in aviation in the 1930s but must have been an allusion to the coal-burning engines of trains and ships, since aircraft were never so powered. It has since been transferred to other vehicles and other endeavors.
See also: coal, on, pour

rake over the coals

Also, haul over the coals. Reprimand severely, as in When Dad finds out about the damage to the car, he's sure to rake Peter over the coals, or The coach hauled him over the coals for missing practice. These terms allude to the medieval torture of pulling a heretic over red-hot coals. [Early 1800s]
See also: coal, rake

rake over the coals

To reprimand severely.
See also: coal, rake

coals to Newcastle

Any unnecessary activity. Before the days of railroading, goods and commodities were transported by water. Coal in particular was shipped to port city of Newcastle before being distributed to the rest of England. Therefore, unless you were the captain of a ship laden with coal, carrying that kind of fossil fuel to Newcastle was a waste of your time and energy.
See also: coal, Newcastle
References in classic literature ?
It came into the scullery no more; but I lay all the tenth day in the close darkness, buried among coals and firewood, not daring even to crawl out for the drink for which I craved.
There must have been a spell either in the tobacco or in the fiercely-glowing coal that so mysteriously burned on top of it, or in the pungently-aromatic smoke which exhaled from the kindled weed.
We took no notice of the joking, but acted, after the manner of greenhorns, as though the Coal Tar Maggie required our undivided attention.
On the other side a brewery waggon was locking with the coal waggon, and an east-bound Kearny Street car, wildly clanging its gong, the motorman shouting defiance at the crossing policeman, was dashing forward to complete the blockade.
As he gave up and stumbled inside his circle, a wolf leaped for him, missed, and landed with all four feet in the coals.
I had to pass coal for the day and night shifts, and, despite working through the noon-hour, I never finished my task before eight at night.
I often marvel these days at the immense quantity of potatoes two or three hundred thousand dollars will buy, or bread, or meat, or coal and kindling.
These furnaces, constructed of fireproof brick, were especially adapted for burning pit coal, with a flat bottom upon which the iron bars were laid.
It is equal to that produced by the combustion of a stratum of coal surrounding the sun to a depth of forty-seven miles.
As soon as we came to the inn, Ransome led us up the stair to a small room, with a bed in it, and heated like an oven by a great fire of coal.
You simply can do nothing, neither great nor little-- not a thing in the world--not even marry an old maid, or get a wretched 600-ton cargo of coal to its port of desti- nation.
Suddenly he took up the poker and broke the large coal fiercely.
When it was dark, and he sat before the coffee-room fire, awaiting his dinner as he had awaited his breakfast, his mind was busily digging, digging, digging, in the live red coals.
Tongs, pincers, large ploughshares, filled the interior of the furnace, and glowed in a confused heap on the coals.
The coldness of the human heart," he said, with a grin, "will keep the creature in his present condition until I can reach home and revive him on the coals.