6.2" Trent Agate With Stibnite & Realgar - Oregon
The white bordered photo is a backlit photo of the specimen, explaining the color change between the black and white bordered photos. The depth of the stibnite crystal formations can clearly be seen in this backlit photo.
Like many other agates, Trent agates form by deposition of microscopic silica crystals in concentric layers within cavities of rocks. The colors of the agate are dependent on impurities within the silica-rich solutions, which in this case are a result of the arsenic, realgar and stibnite.