This site is now on China Lake Naval Weapons Center (formerly Camp Irwin) in a restricted area and is no longer accessible to the general public. The site has been closed about 30 years. The site is located 25 miles southeast of of Ridgecrest, on the south flank of Robbers Mountain. It is labeled as Lead Pipe Springs on the Pilot Knob 7.5 minute Topographical map. The adjacent Eagles Craig map is also of use.
According to AOS member Bill Burns, there is precious opal in thundereggs, about one in a hundred. The opal could only be seen after splitting the thundereggs. Bill collected here before the site was closed and has some samples. The opal is a white based opal, similar to Coober Pedy.
Below are references for the site, found at http://csd.unl.edu/csd/programs/lexicon/framelex.html, an index for agates.
Lead Pipe Springs Agate, for Lead Pipe Spring, 35o 27' 15" N and 117o 10' 51" W, San Bernardino County, California. Eakle (1922, p. 88) fine blue chalcedony occurs two miles northeast of Lead Pipe Springs.
Hagar (1946. p. 8-9.) listed this site.
Blue chalcedony in a red rhyolite porphry matrix, ...formerly known as ACal-Azur@, ....thunder eggs containing high quartz, tridymite, chalcedony, low quartz, and opal (Rogers, 1947, p. 1256)
Blue, sagenitic, and moss agates; this site is now on a military reservation. (Perry, 1961, p. 310).
Zeitner (1964, p. 349) reported a royal blue chalcedony that had been collected from here as early as 1911, but she did not cite a source for this information.