Try these links at a rock blog I just found. It may be your best chance to see this agatized fossil material on the screen:
These are southern Californians talking mostly about about collecting in San Luis Obispo county and points south, but the principles of spotting it on a beach apply elsewhere and the Northern California material seems comparable.
Who can help me compile a full list of ALL the California collecting localities for this material?
AND, who can tell us its AGE, more or less? According to Robert Boessenecker, student of fossil marine mammals of the California coast: “The material from Ano Nuevo and Pescadero is the Mio-Pliocene Purisima Formation… Material from San Luis Obispo County is probably middle-late Miocene, and likely from the Sisquoc and Monterey Formations.”
BUT . . .
The fossil bone that sets the world standard as the finest, at least for the gem cutter or jeweler, is DINOSAUR bone from the American Southwest. Take a look at these pictures: http://differentseasons.ganoksin.com/blogs/2009/01/09/agatized-dinosaur-bone/
The colors and patterns in these pictures of polished dinosaur bone gems (by Mark Anderson of Different Seasons) are truly amazing . . . Enjoy!
(Originally blogged February 14, 2009 – Wintertime! – collecting season…)