Mining

Subcategories:
  • No categories
Clear

Entry Category: Mining

Antimony Mining

Antimony (Sb) is a hard, brittle, silver-white metal with a relatively high specific gravity (6.69) and a relatively low melting temperature. Antimony is a constituent in some alloys. The presence of this metal hardens the alloy, lowers the melting point, and decreases contraction during solidification. The metal’s main use is to impart stiffness and hardness to lead alloys. Antimony compounds are used in medicines, paint pigments, enamelware glazes, and as fireproof coatings on clothing. They are also used in the rubber and patent-leather industries. Many minerals contain antimony; however, stibnite and antimonial lead ores are the main sources of the metal. Stibnite (Sb2S3) and its alteration oxide, stibiconite (Sb3+Sb25+O6(OH)), were the only minerals mined in Arkansas for this metal. Stibnite …

Bauxite Mining

Bauxite is the principal ore of aluminum and is a mixture of aluminum oxides and hydroxides that formed from intense chemical weathering of a soil in tropical environments. Soils formed under these conditions are termed laterites. In Arkansas, the aluminum-enriched soils are the result of the decomposition and lateritic weathering of nepheline syenite, an intrusive igneous rock. During the weathering process, leaching by rain, groundwater, and salt spray decomposed the original syenite minerals (feldspar and nepheline). Weathering removed much of the silica and concentrated the newly formed aluminum oxides and hydroxides as the rock termed bauxite. Geologically, the soils formed from syenite and weathered to laterites in the Paleocene Epoch (65–55 million years ago) along the west edge of a …

Coal Mining

Coal fields in Arkansas are located in the Arkansas River Valley between the western border of the state and Russellville (Pope County) an area only about thirty-three miles wide and sixty miles long. Until about 1880, most coal mined in Arkansas was used near its original location, often to fuel the fires of blacksmiths. Between 1880 and 1920, coal was Arkansas’s first mineral/fuel output, used especially for locomotives and steam-powered machines, as well as for heating homes and businesses. After 1920, oil and oil byproducts pushed aside the popularity of coal as a fuel, and mining of coal decreased. Much of the coal mined in Franklin County and Sebastian County around the year 2000 was used in the manufacture of …

Crushed Stone Mining

Crushed stone is an angular form of construction aggregate, made by breaking quarried rock into fragments that may be sorted, sized, and recombined into a variety of products. Crushed stone is typically quarried—that is, mined using benching methods (carrying out work from a ledge in a mine or quarry) and explosives, as opposed to the mechanical digging used for extracting sand and gravel. Consolidated rock is cut into vertical ledges, so that drilling can be done from above to place explosives within the wall for proper breakage of rock during mining. Benches typically vary from twenty to sixty feet in height, depending on how competent the rock is. The quarry stone is normally run through a primary crusher and then …

Diamond Mining

Almost 100 million years ago, in what is now Pike County, nature created one of the world’s most unusual diamond-bearing formations, the big volcanic “pipe” that now serves as the centerpiece of Crater of Diamonds State Park. Famous today for recreational mining, the eroded old crater once inspired generations of diamond hunters to dream of commercial success. The history of that long quest—the expectations, the contention, and the repeated frustration—is, in itself, an invaluable legacy of the Arkansas diamond field. Unlike the typical diamond pipe, the formation in Pike County accumulated in various stages as molten rock deep within the earth’s mantle swept up through a shallower zone where diamonds had crystallized long before and then worked its way to …

Dimension Stone Mining

Dimension stone is defined as rock that is removed from its original site to be used with minor alteration (rough stone) and rock that is broken, sawn, and/or ground and polished (cut or dressed stone) for use as building and/or ornamental stone. While most of the high-quality dimension stone produced in Arkansas is used in state, some is shipped to markets worldwide. Limestone and sandstone are used as dimension stone in Arkansas. Historically, much nepheline syenite was used as hand-worked building stone in the late nineteenth and early twentieth centuries in the Little Rock (Pulaski County) area, but beginning in the middle 1940s, those labor-intensive activities gave way to the use of crushed stone for syenite. A small market exists, …