A coal breaker was a coal processing plant which broke coal into various useful sizes. Coal breakers also removed impurities from the coal (typically slate) and deposited them into a culm dump. The coal breaker is a forerunner of the modern coal preparation plant. Generally speaking, a coal tipple was typically used at a bituminous coal mine, where removing impurities was important but sorting by size was only a secondary, minor concern. Coal breakers were always used (with or without a tipple) at anthracite coal mines. While tipples were used around the world, coal breakers were used primarily in the United States in the state of Pennsylvania (where, between 1800 and the mid-20th century, nearly all the world's known anthracite reserves were located). At least one source claims that, in 1873, coal breaking plants were found only at anthracite mines in Pennsylvania.