About 40 miles northwest of the Prineville area, just north of Madras OR. on Hwy 97 is Richardsons Rock Ranch. Richardsons is probably one of the best known thunderegg digs. It has been around for many years not only as Richardsons, but part of Richardsons was also the old Priday beds. The Priday plume beds have not been worked for many years now so this particular material is very rare.