“... This mine is ... owned by Kop Kopcinski. The matrix on these eggs tends to be a darker green than the nearby Lucky Strike specimens, and the agate cores can be just as beautiful, or more so. Kop says these are his favorite eggs. I have seen plumes and stringers of multi-colored moss in these eggs. This is also a fee area, but it is not always open. Inquire at the Lucky Strike Mine...”

 extract of the article from Mark Ketsdever, Hillsboro, Oregon, 2007 :”Thunderegg Agates of the Ochoco Mountains, Oregon, USA”