In 2015, some 356 mines were active in Maryland. According to the 2012 U.S. Economic Census, 54 firms operate mines in the State. With a combined payroll of $60 million, they employ 1,046 people.
Caterpillar bulldozer & conveyor belt dumping coal, Conrail coal yard, Baltimore, Maryland, May 2015. Photo by Sarah A. Hanks.
By the mid-1900s, the mining industry began to decline in Maryland. More buildings were being constructed with brick, crushed stone, and steel. This factor, as well as a decrease in reliance on coal as a fuel source, caused many mines to became less profitable. Some tapped out; others became financial burdens on owners. Consequently, fewer mines were dug, and more shut down.
As many mines were abandoned, they posed safety and environmental risks. Plans and programs to reduce risks and improve former mine sites are overseen by the Mining Program within the Maryland Department of the Environment, and the Interstate Mining Compact Commission.
Drift Mines use horizontal passages to access mineral deposits, when the mineral is located close to the surface, and the vein forms a nearly horizontal sheet.
Shaft Mines employ vertical tunnels to reach far below the surface. They are used when a mineral forms a vertical vein, or lies too deep to reach by other means.
Slope Mines use sloping access shafts to reach mineral deposits. They afford access to minerals not found at the surface, but not deep enough to warrant shaft mining.
Surface Mines extract minerals that are just below the surface, or are too unstable for tunnelling techniques to reach. The term, surface mining, describes all procedures that remove the surface to reach mineral deposits. This method includes open-pit and strip mining, and is used to reach cinder, gravel, and sand.
Coal mines have been a major source of income for Maryland since the early 1800s. Found in the western counties, these mines once exported to all states, and even Europe. By the early 1900s, coal mining here peaked with more than 450 mines in operation, producing over five million tons a year. Since then, despite a dramatic drop in the number of active mines, technological advances have allowed production of more coal per mine with less damage to the environment than ever before.
Today, within the Department of the Environment, the Coal Mining Division oversees and approves all proposed mining plans in the State. The Division also evaluates and approves plans for environmental restoration of lands containing abandoned mines. Approximately 37.1% of all energy produced in Maryland comes from coal. As of 2016, some 59 permitted coal mines operated in the State, producing over two million tons of coal each year. Most are surface mines, while five are underground drift mines.
NONCOAL SURFACE MINES
Noncoal is defined as any mined commodity that is not coal or peat, and is referred to as nonfuel or industrial mineral. Noncoal includes aggregate (used in blacktop, concrete, & plaster), clay, and stone, as well as other minerals.
In 2016, there were 299 noncoal surface mines operating in Maryland. Most are found in southern Maryland (Charles, Prince George's & St. Mary's counties). The Minerals, Oil and Gas Division within the Department of the Environment oversees these mines.
Mined stones are classified by two types: crushed, and dimension.
Crushed Stone is a form of aggregate, and is a base for making asphault, concrete, macadam, and tarmac. Used extensively to pave and construct roads, crushed stone mined in Maryland was valued at $237 million in 2016.
Dimension Stone is any stone that is mined, then altered to required specifications. Once used as a primary building material, dimension stone production has declined greatly over the last century. The value of dimension stone mined from Maryland in 2015 was $728,000.
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