Youngite

Youngite is a variety of agate that is provided a local name for agatized limestone breccia clasts rehealed with bluish-gray chalcedony and drusy quartz. This chalcedony and quartz usually also form around the exterior and lines the vugs of the material. It comes from one location only and is no longer mined, making this rare. Youngite is only found near Guernsey, in Eastern Wyoming. The most notable locale that produced some excellent specimens is the Hartville Uplift. Although specimens are still available from time to time, the Wyoming locations are now closed.

Youngite is a fluorescent rock and can be found in ultra violet or black light displays at many museums. The chalcedony/drusy quartz glows green under Ultra Violet (UV) or black light. The jasper center of this material is called brecciated due to its angular fragmentation. The jasper center varies in color from a light tan, to a pretty peach, brown, reddish, salmon and variations of these colors. The material is very hard and is used in making cabochons and other jewelry pieces. It polishes well and makes excellent display specimens for the collector.