agates

Chalcedony quartz with colorful stripes and interesting inclusions.

Fairburn Agates

Special guest article from Show-Me Rockhounds club members Dan and Connie Snow

Fairburn agate fortification agate

Group picture of Fairburn agates – Dan 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 agate fortification agate

Frog Rock – Dan Snow

Down under agate – Dan Snow
The Conscious Eye – Dan Snow
Fairburn agate – Dan Snow
Fairburn agate – Dan Snow
Water agate – Dan Snow
Finger agate – Dan Snow

Fairburn Agates found by Dan and Connie Snow. Collected from the Fairburn Agate beds of South Dakota and the Oglala National Grasslands in Nebraska.

Spring Forward to the Show
mineral clock with agates and apache tears

Photo by Stephanie Reed

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.

Dyed Agates

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

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

Gem Show Photos Fall 2015

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.

Panorama of the KCI Expo Center Gem Show

An overview of the whole show. Photo by Stephanie Reed

Two women looking at books about rock collecting.

This year we sold books about rocks and where to find them, including the highly desired Gemstones of North America by John Sinkankas.

A man at a laptop with rocks for sale.

Mark selling minerals.

People posing with an aquamarine crystal

President Martin and Webmistress Stephanie looking at an aquamarine. Photo by David Reed

A clear glass jar full of small tumbled chips of Lake Superior agates.

This jar of tumbled chips of Lake Superior agates was part of a kit for making a gem tree, sold by the Show-Me Rockhounds. Photo by Stephanie Reed

Mineral spheres of assorted colors red green blue pink orange

Polished spheres made of minerals from Dave’s Rocks and Carvings (Hamburg, MI). I see rose quartz, tiger’s eye, sodalite, and snowflake obsidian. Can you name all the minerals?

Glass shelves full of interesting minerals and rocks for sale

Mineral specimens for sale from Dave’s Rocks and Carvings (Hamburg, MI) Photo by David Reed

Blue larimar rings jewelry

Gem shows always have lots of jewelry for sale, usually organized by mineral. This is an entire box full of rings made with blue larimar sold by Manichia LLC (Kansas City, MO). Blue larimar is a type of volcanic pectolite found in the Dominican Republic.

colorful lampwork glass beads

Glass beads for sale at Park Design (St. Joseph, MO). You can even watch the beads being made. They can also be found at the Three Trails Trading Post in Independence, MO.

Happy Agate
An agate slab with a happy smiley face in its brown bands.

Smiley face agate photo by Cobalt123 from https://flic.kr/p/dVdpEA

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

Flame and Frost Agates

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.

Red, orange, and yellow plumes shooting up from a white and transparent agate matrix, looking like flames.

Photo by Vítězslav Snášel from http://www.mindat.org/photo-114774.html

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
Photo from Heart of Stone Studio at http://www.heartofstonestudio.com/Wind-Cloud-Agate-Druzy-ZN536
Photo from http://www.northlincolnagatesociety.org/

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.