We hope you are having fun at the show. Don’t forget to set your clocks forward 1 hour for Daylight Savings Time.
Special guest article from Show-Me Rockhounds club members Dan and Connie Snow
Fairburn agates are a form of microcrystalline chalcedony, 100% silicon dioxide with a hardness of 6 ½ to 7 on the Mohs scale. They are also called fortification agates because of their banding. They were formed approximately 300 million years ago in an ancient limestone bed of an inland sea. To hunt Fairburn agates requires looking at every rock and turning many with a rock pick. It is strictly surface hunting no digging, mining, cracking or breaking rocks. The photos shown are exactly the way the agates were found, with no cutting, polishing or tumbling having been done.
Fairburn Agates found by Dan and Connie Snow. Collected from the Fairburn Agate beds of South Dakota and the Oglala National Grasslands in Nebraska.
We interrupt the Spring Gem and Mineral Show to remind you to set your clock forward one hour tonight for Daylight Savings Time.
This clock is from the collection of David Reed. It contains agates, Apache tears (obsidian), a craft store clock kit, and lots of resin. It looks pretty good with his other rock clock.
Have you ever seen dyed agates and wondered how they get such brilliant colors? The process is more simple than you might think. A company buys banded agates in bulk and soaks the slabs in certain chemicals for a certain amount of time (in a fume hood of course). Heat treating may also be required.
But how do they preserve the white stripes that make the agates look like agates? This is simply because some bands are porous and will absorb the dye, but the denser layers and the quartz crystals will remain white because they are too dense to absorb the dye.
(Note: To discourage you from trying this at home, I’m not going to specify the concentrations.)
Red: Iron (II) nitrate for several weeks folllowed by heating to 300° C
Green: Potassium chromate followed by ammonium carbonate plus heating to 440° C
Blue: Potassium ferrocyanide followed by ferrous sulfate
Black: soak in sugar for 3 weeks followed by sulfuric acid for 3 weeks
We had fun selling and buying specimens at the gem show. If you missed it, here are some of the things you can expect to find at a show.
This pattern in this agate from the Czech Republic looks like pussy willows in the spring. What do you think it looks like?
An agate dressed up for Halloween, hanging out at the Tucson Rock and Gem Show 2013. Thanks for following us all the way through Agate Month and learning all about these beautiful minerals!
If you’d like to see a list of even more types of agates, go here: http://stoneplus.cst.cmich.edu/agate.htm
Shadow agates are hard to photograph, because it’s more of an effect. When you move shadow agates back and forth, you can see deep, dark areas that appear to move. They look like they are deep inside the stone.
These aren’t technically types of agate according to Mindat, but sometimes they will be described this way in rock shops or on rockhound websites. And these pictures are so great I couldn’t possibly pass them up. An agate with red, orange, or yellow plumes in just the right arangement can be called a flame agate, because it looks like fire.
Frost agate describes the cracked finish on these beads (again, it’s not a mineralogical term). They can also be called cracked agate. The frost effect is heightened when they are blue. Whatever they are, I would totally wear earrings made with these beads.
Cloud agates look like they contain clouds. They can have a gray or transparent matrix and the inclusions are usually white and foggy to look like clouds. The one on the left has a bit of a drusy effect which makes it look like a puffy cumulus cloud. The cloud agate on the right has a blue “cloud” inside. The North Lincoln Agate Society has given its friend some googly eyes.