The Stonedog's Mercantile
Most agates you find are alluvial (in rivers or streams). Not too often do you find agates that are still in situ in the volcanic rock in which they were formed. If you are lucky at this Keep Cool site, you will be able to recover agate that formed as an amygdaloid in a void in vesicular volcanic rock. Access is from MT Hwy 200 east of Lincoln via county and forest service roads. Allow thirty minutes from the highway to the collecting site. A rock hammer and chisel may be nice to have along.