Anthracite, the smokeless hard coal that blockade runners and railways prized
Most coal smokes and stains; anthracite does neither. This dense, glossy fuel burns with a short blue flame and almost no soot, which is why Confederate blockade runners fed it to their boilers to stay hidden, and why one American railway advertised spotless white gowns to its passengers.
Anthracite is the highest rank of coal, with between 86 and 97 percent carbon and more energy per kilogram than any other type. It forms where rock has been squeezed and heated, along the flanks of big mountain ranges, and chemically sits between ordinary bituminous coal and graphite. It is harder and denser, does not dirty your fingers, and conducts heat so well that a lump feels noticeably cold in a warm hand.
Those same qualities made it awkward at first. It needs a higher temperature to catch and a draught from below to keep burning. A popular Pennsylvania legend credits a hunter, Necho Allen, who in 1790 supposedly woke beside Broad Mountain to find his campfire had set an outcrop alight. In 1808 John and Abijah Smith floated the first commercial load down the Susquehanna, and output eventually peaked above 100 million tons in 1917.
The hot blast, introduced in 1828, preheated air for furnaces, and within 15 years anthracite was fuelling 45 percent of American pig iron before coke took over. It then heated homes across the northern states until oil and gas displaced it. The Delaware, Lackawanna and Western Railroad burned it in passenger engines, billing itself the Road of Anthracite, with a white-clad heroine called Phoebe Snow.
Today it is a niche. It makes up about 1 percent of the world's coal reserves, and northeastern Pennsylvania holds the largest known deposits, yet China mines more than three-quarters of global output, mostly for power. Welsh commercial mining, which dates to medieval pits near Saundersfoot, ended in 2013. One Pennsylvania company even sprayed its product blue at the mine to stand out.
Source: Anthracite
