Crab Orchard Stone

During a break at the AGU meeting in December, I was talking stone with Sid Perkins, who writes about geology for Science News. He told me about a rock with the wonderful name of Crab Orchard Stone. Eight months later, I am finally writing a bit about it.

Photograph courtesy of Sid Perkins, who retains the copyright.

Named for Crab Orchard, Tennessee, which in turn is named for groves of crabapple trees, the rock first reached national prominence in the 1920s. Prior to that, it had mostly gone into flagging, sills, and foundations. According to a 1961 report by the U.S. Bureau of Mines, large scale quarrying started around 1926, when architect Henry Hibbs sought stone for Southwestern University in Memphis. Several quarries still produce the stone, which in 2001 went into and onto the Country Music Hall of Fame, in Nashville.

Photograph courtesy of Sid Perkins, who retains the copyright.

The Crab Orchard is a beautiful sandstone ranging in color from tan to blue gray with shades of yellow, pink, purple, and brown. Adding to the appeal, the colors appear as lines and swirls, many of which form geometric patterns. Dense and fine-grained, it is “relatively impervious to moisture, and comparatively inert to acid or fumes encountered in manufacturing areas,” or so wrote the Bureau folks in 1961. They also observed that dirt and soot could be readily washed off. What more could one want?

Photograph courtesy of Sid Perkins, who retains the copyright.

The Crab Orchard stone is remarkably homogeneous, containing on average about 93% silica. It occurs in beds of uniform thickness, which allowed quarrymen to produced a single sheet that measured 111 feet long, 8 1/2 feet wide, and 3 inches thick. More often, the slabs used in buildings are smaller, and appear as treads, copings, garden furniture, wainscoting, memorials, and roofing.

Photograph courtesy of Sid Perkins, who retains the copyright.

Some controversy exists about deposition of the Crab Orchard stone. Some geologists propose that it occurred in braided streams and some that deposition took place in “back-barrier, tidal flat, and tidal channel or delta sub-environments within a barrier or marine-dominated deltaic system.” But all agree that deposition took place in the Pennsylvanian.

Photograph courtesy of Sid Perkins, who retains the copyright.

Recently, Sid was back in Crab Orchard and sent me a wonderful series of photographs of the stone. The above shots give a feel for the variety of colors and uses. If you are interested in using any of them, please contact me and I will pass your name on to Sid.