BUILDING AND ORNAMENTAL STONE FROM THE PRECAMBRIAN ROCKS OF WISCONSIN: A REVIEW OF HISTORIC PRODUCTION AND FUTURE PROSPECTS

The Precambrian rocks of northern Wisconsin have been an important source of dimension stone since the mid nineteenth century. A variety of predominantly granitic rocks ranging from Archean gneiss to gabbros and sandstones of the Middle Proterozoic Midcontinent Rift have been quarried for building and monumental use.

The red granite of the Wausau area, the Wisconsin state rock, is the only granite quarried in significant quantity today. A small amount of gray granite from northeast Wisconsin is quarried for monuments and specialty uses. No quarries produce building stone today, however, many structures built with Wisconsin granite survive throughout the state. The red-brown Montello granite is no longer quarried but it was popular in the late nineteenth century for building and memorials, including Ulysses S. Grant's tomb in New York.

Granites and metarhyolites of south-central Wisconsin were less popular as building and monument stone, but were an important source of stone paving blocks. Examples can still be found in Milwaukee, Chicago, and cities throughout the Midwest where blocks were shipped by rail. The rapikivi granites weathered quickly and were only suitable for interior use, a rare example being the Wisconsin Capitol.

Gabbro from the Midcontinent Rift was quarried for building and monumental use, but the best known stone from the rift was the Lake Superior sandstone, which was quarried along the Bayfield peninsula and in the Apostle Islands. Large quantities were shipped via the Great Lakes, and many historic buildings still stand throughout the Midwest.

Today only one major granite producer is active, down from more than 20 in 1900. Small operators have shown interest in producing stone for restoration and specialty products, but foreign competition makes it unlikely that Wisconsin will again be a major producer of hardrock dimension stone.