Barite with Quartz

specimen number:
2292428

location:
Richardson Ranch, Jefferson Co., Oregon, USA

description:
A thunder egg half, this cut and polished. There is a large cavity present lined with botryoidal quartz and scattered throughout with blue bladed crystals of barite. Interesting locality example for the species.

The Richardson Ranch, located near Madras in Jefferson County, Oregon, is situated within the Oligocene to Miocene volcanic rocks of the John Day and Clarno formations. Geologically, this historic ranch is famous for its rhyolitic ash-flow tuffs and lava beds that cooled to form dense deposits of agate-filled thundereggs and nodules. Historically operated as a working cattle ranch by the Richardson family, it opened to the public as a world-renowned dig-your-own rockhounding site in the mid-twentieth century. While the ranch is most notable for its diverse agate beds, the regional hydrothermal fluids that altered the volcanic glass also deposited a variety of secondary minerals within the rock cavities. Among these minor minerals are barite crystals, which occur occasionally in the area as white to pale-colored tabular plates or bladed clusters alongside calcite, zeolites, and microcrystalline quartz.

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