Coal
Coal (from the Old English term col, which has meant "mineral of fossilized carbon" since the 13th century) is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Read more about Coal.
Famous quotes containing the word coal:
“Writing is to descend like a miner to the depths of the mine with a lamp on your forehead, a light whose dubious brightness falsifies everything, whose wick is in permanent danger of explosion, whose blinking illumination in the coal dust exhausts and corrodes your eyes.”
—Blaise Cendrars (1887–1961)
“... gathering news in Russia was like mining coal with a hatpin.”
—Mary Heaton Vorse (1874–1966)
“Mr. Christian, it is about time for many people to begin to come to the White House to discuss different phases of the coal strike. When anybody comes, if his special problem concerns the state, refer him to the governor of Pennsylvania. If his problem has a national phase, refer him to the United States Coal Commission. In no event bring him to me.”
—Calvin Coolidge (1872–1933)