sedimentary
Fairburn Agate
Cryptocrystalline Quartz (SiO2) with inclusions
Hardness: 6.5-7 Mohs; Color: Red, white, pink, and grey banding; Luster: Vitreous to waxy; Structure: Microcrystalline; Conchoidal fracture.
- Hardness
- 6
- Color
- Red, white, pink, and grey banding
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Red, white, pink, and grey banding; Luster: Vitreous to waxy; Structure: Microcrystalline; Conchoidal fracture.
Formation & geological history
Formed in limestone cavities during the Pennsylvanian-Permian periods, subsequently weathered out and concentrated in alluvial deposits during the Oligocene.
Uses & applications
Highly prized as a collector's stone, used in jewelry, lapidary arts, and as a state gemstone.
Geological facts
The Fairburn Agate is the state gemstone of South Dakota. It is distinctive for its 'fortification' patterns (sharp-angled banding) and unique color combinations.
Field identification & locations
Identified by sharp, parallel, colorful banding within a chert-like matrix. Found primarily in the Fairburn Agate beds of southwestern South Dakota and northwestern Nebraska.
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