Anthracite and it is found most abundantly in areas that have been subjected to considerable stresses and pressures, such as the flanks of great mountain ranges. Anthracite is associated with strongly deformed sedimentary rocks that were subjected to higher pressures and temperatures (but short of metamorphic conditions) just as bituminous coal is generally associated with less deformed or flat-lying sedimentary rocks. For example, the compressed layers of anthracite that are deep mined in the folded Ridge and Valley Province of the Appalachian Mountains of the Coal Region of East-central Pennsylvania are extensions of the same layers of bituminous coal that are
Anthracite times been futile, and several such combustion areas exist today. The existence of an underground combustion site can sometimes be identified in the winter where fallen snow is seen to be melted by the warmth conducted from below. Proposals for harnessing this heat as geothermal energy have not been successful. A vein of anthracite that caught fire in Centralia, Pennsylvania in 1962 has been burning ever since, turning the once-thriving borough into a ghost town. Among current producers, Russia, China and Ukraine have the largest estimated recoverable reserves of anthracite. Other countries with substantial reserves include Vietnam and North Korea.