The geochemistry of agate and chalcedony in volcanic rocks represents an intricate record of silica precipitation and crystallisation processes occurring under variable thermal and chemical conditions ...

Forbes contributors publish independent expert analyses and insights. David Bressan is a geologist who covers curiosities about Earth. Chalcedony, from the Greek trade city of Kalzedon, is a variety ...

The mineral chalcedony is a microcrystalline type of quartz which replaces the original calcium carbonate of the coral and forms into agate. Grains of sand and pieces of the original calcium carbonate ...

L-14 (Little Colorado River Chert/Quartzite/Petrified Wood/Chalcedony/Agate): Not direct collection from outcrop. Provenience includes samples from gravel deposits. Unknown collection procedure.

Van-hal West African School British School Baron Gilles Ghez Colin Almack Albino Galvano Thai School, 17th Century Northern European School, 18th Century Polia Pillin Artists > Agate > Artworks > An ...

An Antique Victorian, Gold, Chalcedony Agate and Turquoise Agate and Turquoise Brooch. Gold 3cm.

When it is viewed with light shining from behind, this polished slice of agate reveals an internal pattern with a likeness of HM Queen Elizabeth II. The specimen is currently on display at the Museum ...