| Back to e-WV
The West Virginia Encyclopedia
| Back to e-WV
The West Virginia Encyclopedia
The rocks of West Virginia are overwhelmingly sedimentary in origin and generally lack eye-catching mineral specimens or large deposits of metallic ores. However, many sedimentary rocks are important to our modern industrial society, and mining these deposits adds to the state’s economy by providing construction materials, chemical feed stocks, and jobs. The main limiting factor affecting the marketability of industrial minerals is transportation costs. These materials tend to be heavy and bulky and largely limited to the coal market.
Limestone and dolomite are sedimentary rocks formed in warm, shallow seas. Known as carbonates, they are mined for construction aggregate and for use in road building, agricultural lime, coal mine safety dust, in coal-fired power plant scrubbers, acid mine drainage neutralizers, and for other uses. Highway construction and increasing needs for pollution controls associated with coal mining and utilities should result in an increased demand for carbonate products.
Most of the state’s limestone production comes from the eastern counties, where the major carbonate formations are exposed and accessible. Geologically, these limestones come from groups laid down in the Paleozoic Era, mostly from the Mississippian Period (ending 310 million years ago) and earlier. Some come from as early as the Cambrian Period, which ended 500 million years ago. In the central and western parts of the state, these rock strata are too far beneath the surface to be mined. West Virginia has sandstone formations suitable for many purposes. Currently, most sandstone is produced from Pennsylvanian Period units, geologically younger than most of the limestone quarried in West Virginia. The sandstone is quarried from parts of the state distant from carbonate supplies, replacing limestone as a construction aggregate. An exception is the Oriskany sandstone, a high-purity quartz arenite, mined near Berkeley Springs. The Oriskany product can be used for a wide variety of applications, including making glass, stoneware, and abrasives. In the past, sandstones have been quarried for building stones, cobble and curb stones, and millstones. There is little market for these products today.
Most of West Virginia’s economic sand and gravel deposits occur in alluvial and terrace deposits and along the Ohio River, formed as outwash deposits during melting of Pleistocene glaciers. The material is dredged from the river channel or excavated from the adjacent terraces. Deposits of limited extent and quality occur along streams in other parts of the state, but production there is generally small and intermittent. Demand for sand and gravel is dependent on the number and location of major construction projects.
West Virginia has enormous reserves of clays and shales that are suitable for the manufacture of brick, cement, and clay dummies used in blasting. The brick and cement manufacturers use shales of the Ordovician-age Martinsburg Formation, and the clay dummies are produced from the Pennsylvanian-age Bolivar Fire Clay. Many Pennsylvanian-aged clay deposits were once mined for making bricks, especially for paving roads. Additionally, there are large deposits that can be used for producing lightweight (expanded) aggregate, refractories, and similar products. Limited demand and high transportation costs currently restrict exploitation of these resources.
Salt was a necessary and scarce commodity during frontier times and was recovered from various natural seeps known as ‘‘licks.’’ Salt was produced commercially at natural seeps and very shallow wells where the Kanawha River crosses the Warfield Anticline slightly upstream of the mouth of Campbells Creek, near Charleston. The anticline brings the sandstones of the New River Formation, which are known as the ‘‘salt sands’’ by drillers due to the presence of saltwater or brines, closer to the surface. Salt was recovered from the salt brine by evaporative boiling in large kettles and pans. Lesser amounts were similarly produced below the falls of the Little Kanawha River. It is interesting to note that petroleum was an unwanted byproduct of salt production.
Modern brine production is from deep wells drilled into the Silurian Salina Formation. These salt deposits, formed by the evaporation of ancient seawater, are more than 50 feet thick in much of the Northern Panhandle and north-central portion of the state. These deposits lie between 5,000 and 9,000 feet below the surface. Fresh water is pumped through an injection well drilled into the salt zone, dissolving the salt. The resulting saline solution is pumped to the surface through a nearby production well. It is used as a feedstock for the manufacture of chlorine, caustic soda, and derivatives for a variety of chemical processes.
Iron was as essential to pioneer life as was salt, and needed for a variety of agricultural and household purposes. Since transporting heavy iron implements was difficult in the days of horse and wagons, local iron industries developed at an early stage in West Virginia’s history wherever ore could be found. Small, workable deposits of iron minerals occur in many areas of the state, and small furnaces were located in these areas to smelt the ore and produce raw bar iron for the pioneer blacksmiths.
Iron ores found in West Virginia occur in thin, isolated deposits within sedimentary rocks. The ore minerals are generally hematite (Fe2O3) and side rite (FeCO2) and are generally mixed with many impurities. Improved transportation methods and the richer iron ore beds discovered around Lake Superior lowered costs, resulting in the inability of the local iron ores to compete economically.
Written by Bascombe M. Blake Jr.