For American collectors the so-called Fairburn agates represent the ideal type of an agate beside the Laker agates. In them unite intensive colour, strong contrast and sharp-drawn fortification-banding. These agates are designated after the city Fairburn in the southwest South Dakotas, one of the first places of discovery of these agates.
Agates of this type are found into the federal states Nebraska and Wyoming too. These originally in sediments formed agates can be only gathered today with much trouble in the “badlands” of above-mentioned states.
Two geological formations are important in connection with “Fairburns”: the Minnelusa formation - in those the agates developed - and the Chadron formation, which consist of eroded remainders of the Minnelusa formation. In the badlands is far common the agate-bearing Chadron formation.
In former times most Fairburns - because of theirs often only partly received pattern - became polished. Nowadays the stones are mostly left in their original feature. So the lively coloring is better preserved.
Often this decomposition-conditioned colorization is only in the outermost layers of the agate. If one saws it, the stone loses usually at coloredness and always at contrast.
In reverse relation to their frequency the price for good Fairburn agates reached heights not any longer comprehensible for the European collectors.
An excellent book over Fairburns was written of the agate collector Roger Clark in co-operation with his wife Mary Jane Clark. (All photos of this Internet-publication over Fairburns come likewise of it!) Unfortunately it was published so far only in English.