SIC 1422 Crushed and Broken Limestone

Contenidos

• NAICS CODE(S).
• FURTHER READING.

SIC 1422

This industry consists of establishments primarily engaged in mining or quarrying crushed and broken limestone, including related rocks, such as dolomite, cement rock, marl, travertine and calcareous tufa. Also included are establishments primarily engaged in the grinding or pulverizing of limestone, but establishments primarily engaged in producing lime are classified in SIC 3274: Lime.

NAICS CODE(S)

212312

Crushed and Broken Limestone Mining and Quarrying

Crushed limestone production is the largest of three related industries that extract and process nonfuel, nonmetallic minerals. Primarily employed as aggregate, which refers to a wide number of sand, gravel, and stone mixtures, crushed stone is an essential component of the U.S. infrastructure because of its use in the construction of highways, airports, river locks and dams, railroad ballast, and breakwaters. It is, however, considered a "high-volume, low-value commodity" with relatively stable prices since the 1970s, according to the U.S. Geological Survey.

The crushed stone industry is the largest nonfuel mining industry in the United States, with 3,100 active quarries, 70 underground mines, and 190 sales/distribution yards in 49 states as of 2005. Limestone and dolomite accounted for the vast majority—70 percent in 2005—of crushed stone production and sales in the United States. The essential make-up of limestone is calcium carbonate (Ca Co3). If 10 percent or more of magnesium carbonate is present it is called "magnesian" or "dolomitic" limestone. The term "limestone" usually acknowledges the presence of dolomite.

After growing by an average of 3 percent in the late 1990s, crushed stone production began to decline in the early 2000s, falling by 2 percent to 1.49 billion tons in 2003. Growth resumed in 2004 with a 3.2 percent increase in production, followed by production of 1.66 billion tons of crushed stone consumed in 2005. Usage for 775 million tons, a little less than half the total production, was reported to the U.S. Geological Survey: 84 percent was used as construction aggregates for highways and roads; 13 percent for chemical and metallurgical uses, including cement and lime manufacture; 1 percent for agricultural uses; and the remaining 2 percent for special and miscellaneous uses and products.

In the past, most crushed and broken stone was mined from open quarries. Current trends favor underground mining. Underground...