STONE AND STONE PRODUCTS

WHAT TYPES OF STONE ARE PRODUCED IN ILLINOIS?

Limestone and dolomite are the most abundant rocks quarried in Illinois. Small amounts of marble, limestone, and sandstone for building stone are also produced. In addition, some glacial boulders and cobbles are used for rock gardens and in home construction. The crushed limestone industry is Illinois’ most important rock products industry.

WHAT ARE LIMESTONE AND DOLOMITE?

Limestone is a sedimentary rock that consists chiefly of calcite, which is composed of calcium, carbon, and oxygen. Dolomite is a variety of limestone that contains considerable magnesium in addition to the other elements. Limestones were deposited on the floors of ancient seas that repeatedly covered most parts of Illinois. Shelled creatures, corals, and coral reefs helped build up the thick limestone deposits (figs. 13 and 14).

Figure 13—Piece of limestone largely made up of fossil brachiopod shells.

WHERE ARE LIMESTONE AND DOLOMITE QUARRIES LOCATED IN ILLINOIS?

Limestone and dolomite quarries are located along the southern, western, and northern margins of the state where the thick deposits of these rocks crop out at the surface. Although bedrock was deposited in horizontal layers, it has since been downfolded into the Illinois Basin whose center is in southeastern Illinois. Thus, the thick limestones and dolomites that are quarried along the margins of the state are too deeply buried to be quarried in the central part of this basin (fig. 15).

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Figure 14—Fossils commonly found in Illinois rocks.

Strophomena 1×

Paleoneilo 1×

Ctenodonta ⅔×

Dolmanites ½×

Archimedes 1×

Hormotoma Polygyra 1×

Mucrospirifer 1½×

Atrypa ⅔×

Crinoid Columnais 1×

Halysites ⅔×

Hexagonaria 1×

Microcylus 1×

Streptelasma ⅔×

Lithostrationella ½×

Lophophyllum 1×

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Figure 15—Diagrammatic cross section of the Illinois Basin.

MISS. RIVER

Waterloo

Mt. Vernon

ILLINOIS

WABASH RIVER

INDIANA

New Albany

OHIO RIVER

ARE ANY STONE QUARRIES LOCATED IN THE AREA UNDERLAIN BY THE ILLINOIS BASIN?

Yes. In the area underlain by the basin, stone quarries are operated in younger, thinner rock strata of Pennsylvanian age. These strata also overlie the thick limestones and dolomites quarried along the margins of the state. The quarries located within the basin area produce stone for agricultural limestone, roads, and other purposes.

HOW AND WHERE ARE LIMESTONE AND DOLOMITE USED?

Millions of tons of stone are crushed annually to produce aggregate for use in making concrete roads and buildings, for road surfacing, and for agricultural limestone. Agstone is applied to farmlands to neutralize soil acidity, improve soil structure, add calcium and magnesium, and promote conditions favorable for the utilization of soil materials by plants. Large quantities of limestone are used in making lime and cement. There are three cement plants 22 in northern Illinois—two at LaSalle and one at Dixon—and one in southern Illinois, at Joppa.

Small amounts of stone are used for making alkalies and glass, for railroad ballast, for building stone, for dusting coal mines to prevent coal dust explosions, and for ingredients in mineral feeds for livestock.

HOW MUCH STONE DOES ILLINOIS PRODUCE?

A production of about 36 million tons of stone in 1963 was valued at almost $48,000,000. The cement made from Illinois limestone in the same year was valued at $32,000,000.