Monday, January 04, 2010
It struck me that you may not know what an agate is in California -- I certainly didn't until my daughter moved here. It's a clear stone that's been polished by the waves and is usually marked by swirls of what I call "white paint." This picture shows my own collection, found since I moved here two years ago. I have yet to find anything very large, but you can get an idea what they look like and how beautiful they are.
For those desiring a more scientific explanation, I copied the paragraph below from an article in a local weekly a couple years ago:
"Wave-polished translucent agates ... are found .... by eager collectors who brave the hazards of being swept out to sea by rogue waves. Agates consist of microscopically crystallized silica (silicon dioxide), called "chalcedony." They often show growth bands. They originate in the hellish conditions of volcanic eruptions, followed by millenia of gentle soaking in warm groundwaters. These "geothermal" waters slowly precipitated the chalcedony in cavities produced by volcanic steam."