“... My two partners and I have owned these claims ( see also Killer Green - red.) for nearly 2 years now, before then it was held by the Mt Hood Rock Club.
... The claims are located high in the Ochoco Mountains approximately 20 miles Northeast of the town of Prineville. They are adjacent, with a small annual creek running between the diggings. The elevation of the claims is around 4,500 feet, and the landscape is dotted with large boulders and Ponderosa pine trees. The scenery is beautiful! The roads that lead to the claims are dirt, and are closed much of the winter due to snow, so the digging season runs from about late April into October. The spur road that goes into the Fallen Tree is very muddy, except in a fairly dry summer, and full of holes and so is not recommended for regular vehicles.
...The thundereggs that are found at the Fallen Tree claim are different than those found at the Killer Green. There are pictures of eggs from both claims that will easily show the difference. Most Fallen Tree eggs have a grey to somewhat maroon matrix, and can be fully or partially filled with agate. The agate can range from clear to blue, with or without waterline or fortification banding. Many contain spherulites within the agate. Fractures are common, especially in eggs close to the surface, due to freezing and thawing cycles. There can be moss or plume inclusions in the agate, I suspect they are mainly zeolite inclusions. Any eggs that are hollow or partially so can have deposits of zeolite minerals within the cavities. Since I am not a geologist, I really don’t know for sure what types of zeolites are present, but Mordenite has been mentioned as a likely one. There are also eggs that contain a white to bluish opal, but it is usually fractured.
... My partners and I hope to work the claim for several years and bring to light many more beautiful specimens. We work the claim by hand so as not to destroy many eggs, but that also makes the work slow and the output from any particular trip may be only a few gallons. The host material at both claims ranges from sticky clay to hard rock, so the digging requires sharp tools and much patience. Of the rough eggs that are cut, perhaps only 10 percent will be nice enough to sell or keep in our collections...”
extract of the article from Mark Ketsdever, Hillsboro, Oregon, 2007 :”Thunderegg Agates of the Ochoco Mountains, Oregon, USA”