La Salle County leads in the produc tion of draintile, fire proofing, and fire brick.
Cook County is the largest producer of terra cotta. Mc Donough County is the leading county in the production of sewer pipe. A large variety of stoneware consti tutes the chief pottery product of the state, with Warren and Mc Donough as the leading counties.
Every kind of clay product classified in the Mineral Resources of the United States is produced in Illinois except china. Illinois ranks first among the states in the value of common brick; second in the value of paving brick, of terra cotta, and stoneware; third in brick and tile products and in enameled brick; fourth in the value of all clay products and in front brick and draintile; fifth in sewer pipe and fireproofing.
Cement, stone, sand, and gravel.—Illinois ranks third among the states in the production of cement, being surpassed by Pennsylvania and Indiana. Prior to 1900 the output of natural cement in the United States exceeded that of Portland cement. In 1900 the output for each kind of cement was 8,000,000 barrels. In 1915 the production of natural cement had declined to 750,000 barrels and the output of Portland cement was 85,000,000 barrels, or ten times as great as in 1900. Of the twelve plants still producing natural cement in the United States in 1915, one is located in Illinois near Utica in La Salle County, where it makes use of the Lower Nlagnesian limestone, the oldest stratified rock outcropping in the state. Important centers of Portland cement manufacture are Oglesby and La Salle in La Salle County, and Dixon in Lee County; while a new plant has been recently erected at Golconda in Pope County. At these cen ters abundant limestone and shale of proper quality for cement lie near the surface and can be readily quarried. So abundant and so widely distributed arc the raw materials for Portland cement that its increased use for struc tural work will tend to conserve the more limited supplies of wood and iron.
Limestone is the chief product of Illinois stone quarries.
About 75 per cent of the output is used as crushed stone for concrete road metal and railroad ballast. Lime used for mortar in building operations is made from limestone, and increasing quantities of fine-ground limestone are being used for soil improvement throughout the state, more especially in the southern counties, where the soils are more acid than else where. Illinois limestone is also used as flux in blast furnaces for smelting iron, for riprap, rubble, and in a small measure for building stone.
Sand and gravel are found in places in the glacial moraines, in the valley trains leading out from the moraines, along streams, and along the lake shore. The sand produced in Illinois is used mainly for building purposes. Other uses are for glass manufacture, molding, paving, and for locomotives. Glass sand is obtained largely from the St. Peter sandstone along the bluffs of the Illinois River in the vicinity of Ottawa. It forms the basis of important glass and bottle factories at Ottawa and Streator. Gravel is widely used for concrete and for road-building.
Sulphuric acid and pyrite.—The many uses for sulphuric acid, especially in the manufacture of munitions of war, has led to a rapid expansion of this industry in the years during the war. The value of the sulphuric acid manufactured in Illinois in 1915 was $2,000,000, or about 7 per cent of the total of the United States. The production of 1917 was valued at $4,000,000. It is obtained as a by-product in the smelting of zinc and lead, or it may be manufactured directly from sulphur or from pyrite, which is made up of sulphur and iron. Illinois ranks fourth among the states in the amount of pyrite pro duced. Pyrite in Illinois conies from the coal mines. The production is made up of small quantities from many mines, the chief supply coming from mines in Vermilion and Madison counties.
Zinc, lead, and silver.—The lead and zinc mines near Galena, in Jo Daviess County, brought about an earlier settle ment of the northwest corner of the state than any other region between the Illinois and Mississippi rivers. Galena was better known to the world for a few years than Chicago. The lead and zinc ores, accompanied by minute quantities of silver, come from the same ore bodies. At first lead was the important product. Now zinc is far more valuable than the lead, and the small silver output of the state is a by-product of the zinc industry. The production in Illinois and elsewhere has been greatly stimulated by the war demands. The zinc mines are found in the Driftless Area of Illinois and Wisconsin; the Wisconsin product is about 7 times as great as that of Illinois. The Illinois product of zinc is about 2 per cent of the total for the United States. Missouri leads in output with more than all the other states combined. Illinois produced, in 1915, 316,000 tons of crude ore from which was made 5,534 tons of zinc "spelter," as the refined product is called.