The Bayfield group is a quartz

Quartz

Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

 sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

 found in Wisconsin along the Lake Superior

Lake Superior

Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...

 coast. It is named for the village of Bayfield, Wisconsin

Bayfield, Wisconsin

Bayfield is a city in Bayfield County, Wisconsin, United States. The population was 611 at the 2000 census. The town is named after Henry Bayfield, a British Royal Topographic Engineer who explored the region in 1822-23....

, but was once known as Western Lake Superior Sandstone.

Prior to the 1900s, Bayfield group sandstone was also variously named Lake Superior Sandstone, brownstone, or redstone, and prefixed by the quarry location. The name was changed to the Bayfield group as its relation to Jacobsville Sandstone

Jacobsville Sandstone

Jacobsville Sandstone is a red sandstone common to the Upper Peninsula of Michigan. Commonly used as an architectural building stone, it is found in the Keweenaw Peninsula and north shore of the Upper Peninsula. Its name is due to the sandstone being quarried largely in Jacobsville, Michigan....

 (once known as Lake Superior Sandstone) is uncertain.

Formation

The Bayfield group is irregularly bedded

Bed (geology)

In geology a bed is the smallest division of a geologic formation or stratigraphic rock series marked by well-defined divisional planes separating it from layers above and below. A bed is the smallest lithostratigraphic unit, usually ranging in thickness from a centimeter to several meters and...

, in contrast to the even, calcareous

Calcareous

Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...

 sandstones in southern Wisconsin. The geological formation is entirely devoid of fossils. The Bayfield group overlies the much thicker Oronto Group

Oronto Group

The Oronto group is a thick group of arkose sandstone and shale located beneath the Bayfield Group in northern Wisconsin, and believed to extend into Minnesota. Because it is almost entirely red in color and highly tilted, it is considered separate from the Bayfield Group. The Oronto group is...

.

The formation, 4300 feet thick, is divided into three: Chequamegon Sandstone, Devils Island Sandstone, and Orienta Sandstone. The Chequamegon Sandstone is a red and white sandstone 1000 feet thick. The Devils Island Sandstone is a 300-foot thick, pink-to-white pure quartz sandtone with significant ripples. The Orienta Sandstone is 3000 feet thick and similar to the Chequamegon Sandstone, but with a higher feldspar concentration.

Properties

The Bayfield group is a predominantly red sandstone, though it varies through lighter colors such as pink, yellow, light brown, gray and white. A minority portion is a dark "brownstone" which is a good building material. The colors occur in bands, though mottling and other irregular markings are common.

As most of the stone's constituents are the end-products of weathering

Weathering

Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...

, it is very resistant to atmospheric action.

Composition

The grains vary from coarse pebbly grits to shale. The finer the grains, the darker their color. The grains are cemented primarily by quartz, with iron oxide coating the grains.

In order of abundance, the Bayfield group is composed of: quartz, feldspar

Feldspar

Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....

 (both orthoclase

Orthoclase

Orthoclase is an important tectosilicate mineral which forms igneous rock. The name is from the Greek for "straight fracture," because its two cleavage planes are at right angles to each other. Alternate names are alkali feldspar and potassium feldspar...

 and plagioclase

Plagioclase

Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series...

), mica

Mica

The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...

, iron oxide (both magnetite

Magnetite

Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...

 and limonite

Limonite

Limonite is an ore consisting in a mixture of hydrated iron oxide-hydroxide of varying composition. The generic formula is frequently written as FeO·nH2O, although this is not entirely accurate as limonite often contains a varying amount of oxide compared to hydroxide.Together with hematite, it has...

), chert

Chert

Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...

, and ferromangesian minerals. The quartz usually comprises about 75% of the stone.

Based on an average of 52 samples, the Orienta Sandstone is composed of: 33.3% nonundulatory quartz, 29.7% undulatory

Undulose extinction

Undulose extinction or undulatory extinction is a geological term referring to the type of extinction that occurs in certain minerals when examined in thin section under cross polarized light. As the microscope stage is rotated, individual mineral grains appear black when the polarization due to...

 quartz, 17.3% potassium feldspar and 9.4% silicic

Silicic

Silicic is a term used to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually put at at least 65 percent. Granite and rhyolite are typical silicic rocks....

 volcaninc clasts. Smaller constituents are 3.9% polycrystalline quartz, 2.3% opaques, 1.6% mafic volcanic clasts, 0.9% metamorphic, 0.7% sedimentary, and 0.4% plagioclase. The heavy mineral suite of Orienta Sandstone is 78% ilmenite

Ilmenite

Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....

, 13% leucoxene

Leucoxene

Leucoxene is a fine granular alteration product of titanium minerals. It varies in color from yellow to brown.It consists mainly of rutile or anatase...

, 3-4% apatite

Apatite

Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...

, 3% zircon

Zircon

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...

, 2% garnet

Garnet

The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name "garnet" may come from either the Middle English word gernet meaning 'dark red', or the Latin granatus , possibly a reference to the Punica granatum , a plant with red seeds...

, and 1% tourmaline

Tourmaline

Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gem comes in a wide variety of colors...

.

Economic use

The only product that Bayfield group sandstone, the "brownstone" in particular, was used for was as building stone.

In the mid 1860s, brownstone

Brownstone

Brownstone is a brown Triassic or Jurassic sandstone which was once a popular building material. The term is also used in the United States to refer to a terraced house clad in this material.-Types:-Apostle Island brownstone:...

 was popular in the eastern United States. The discovery of the Bayfield group, similar to Eastern brownstones, brought immediate exploitation, and the first quarry opened in 1868 on Basswood Island

Basswood Island

Basswood Island is a Wisconsin island in Lake Superior. It is one of the Apostle Islands and a part of the Apostle Islands National Lakeshore....

, operated by the Basswood Island Brownstone Company. A few years prior to 1893, the business was booming. However, the heavy influence of speculators helped lead to a decline that paralleled the Panic of 1893

Panic of 1893

The Panic of 1893 was a serious economic depression in the United States that began in 1893. Similar to the Panic of 1873, this panic was marked by the collapse of railroad overbuilding and shaky railroad financing which set off a series of bank failures...

.

By the time that the quarries could recoup their losses, paler limestones had gained favor, partly due to the "White City" of the Chicago World's Fair

World's Columbian Exposition

The World's Columbian Exposition was a World's Fair held in Chicago in 1893 to celebrate the 400th anniversary of Christopher Columbus's arrival in the New World in 1492. Chicago bested New York City; Washington, D.C.; and St...

of 1893. By 1897, very little stone was being extracted. By 1912, only two quarries remained producing high quality Bayfield group sandstone.