Tennessee marble

Tennessee marble is a type of crystalline limestone found only in East Tennessee, in the southeastern United States. Long esteemed by architects and builders for its pinkish-gray color and the ease with which it is polished, the stone has been used in the construction of numerous notable buildings and monuments throughout the United States and Canada, including the National Gallery of Art, National Air and Space Museum, and United States Capitol^[1] in Washington, D.C., the Minnesota State Capitol, Grand Central Terminal in New York,^[2] and Union Station in Toronto.^[3] Tennessee marble achieved such popularity in the late-19th century that Knoxville, the stone's primary finishing and distribution center, became known as "The Marble City."^[4]

While Tennessee marble is not true marble, its crystalline nature lends it a strong resemblance to marble, especially when polished.^[5] The stone occurs in belts of Ordovician-period rocks known as the Holston Formation^[5] and is quarried primarily in Knox, Blount, Loudon, Union, and Hawkins counties.^[6] While pink is the most well-known color, the stone also occurs in gray, dark brown ("cedar"), and variegated shades.^[6]

The use of Tennessee marble declined after World War II, when cheaper building materials became widely available. There are currently only six active quarries, all operated by the Tennessee Marble Company.^[7] The stone has most recently been used in the floor of the United States Capitol Visitor Center and for the 170-ton "First Amendment" tablet that initially adorned the facade of Washington's Newseum,^[8] as well as the National Constitution Center in Philadelphia, Pennsylvania.^[9]