South Dakota Gemstone or Gem

Fairburn Agate

(Microcrystalline Quartz)

Adopted on February 11, 1966.

The Fairburn agate,  Microcrystalline Quartz, was designated as South Dakota's state gemstone on February 11, 1966. 

The S.D Department of Environment and Natural Resources (DENR) does not keep statistics on the Fairburn agate.

In the literature, Fairburn agates are reported as quite scarce, and highly prized by collectors (Campbell and Roberts, 1985). The price of a Fairburn agate ranges up to $150, depending on the size and quality of the geode (Eric Fritzsch, Geology Museum, South Dakota School of Mines and Technology, personal communication, July, 1993). As with other agates, a larger Fairburn agate is not necessarily a better-quality agate. Agates are primarily used as decorative pieces, as mineral specimens, and in lapidary work.

The state gemstone is the Fairburn agate, a semiprecious stone first discovered near Fairburn, South Dakota. The stone is found primarily in an area extending from Orella, Neb., to Farmingdale, S.D. It is used in jewelry and is a favorite of rock collectors.

Fairburn agates are noted for their strikingly contrasted, thin bands of wonderful natural colors (Sanborn, 1976). Roberts and Rapp (1965) state that the color patterns are generally yellowish-brown with narrow opaque white bands, or dark red with white bands. However, another beautiful combination shows salmon-pink bands alternating with white bands. Other colors included in these agates are black, yellow, grayish-blue and milky-pink.

These agates were originally named after a prolific locality 10 miles east of Fairburn, South Dakota, in the southern Black Hills area. According to Roberts and Rapp (1965), Fairburn agates occur in a broad elliptical belt extending from Creston in Pennington County, South Dakota, to near Orella in Sioux County, Nebraska, with the maximum width approaching 15 miles near Red Shirt, South Dakota. According to Fritzsch (S.D. School of Mines and Technology, personal communication, 1993), the area is more restricted. The Fairburn agate fields cover thousands of acres of very stony land and most of it is rugged terrain, well decorated with cactus, weeds, and cedar trees (Zeitner, 1964).

Fairburn agates may be collected around the Fairburn area where they are scattered on the ground surface. There is no company that collects and markets Fairburn agate.

Agate, like Chalcedony, is a variety of quartz gemstones composed of layers of quartz, sometimes of different colors. Agate usually occurs as rounded nodules or veins in rock such as volcanic lava. The layers of quartz are often concentric. The composition of agate varies greatly, but silica is always predominant, usually with alumina and oxide of iron. Agate comes in most colors. There are several types of agate. Common ones are: blue lace agate, moss agate, tree agate and petrified wood.