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When I first saw a slab of peach and white cabbing material, I thought it looked like a sweet confection; then I saw its name, "Cotton Candy". It fit.Then I showed it to an older rockhound, who authoritatively told me it was "Youngite". Being a curious sort, I decided to find out if they were one and the same thing. Frankly, I thought it was likely they were, but appearances can be deceiving.
Youngite (SiO2 ) For many years, this was a popular slabbing material that was not terribly hard to find even though it was only mined in one place inside the Youngite caves near the Glendo and Guernsey reservoirs in Guernsey, Wyoming. The online expert on this stone is Mike Nelson, I got my information from him personally and his blog site, check it out: Click Here
Mike says Youngite is a brecciated reddish-brown to peach jasper that was then re-healed by deposition of cream-colored chalcedony. Often the entire rock is then covered by druzy quartz crystals. At one time Youngite was fairly common on the market as collectors were able to pull numerous specimens “off the walls” in Youngite cave(s) and voids near Guernsey. He says he understands that the caves are in the Guernsey Limestone and the breccia clasts are actually derived from the limestone.
|Image Credit: Midat.org|
This image shows the common exterior with botryoidal drusy quartz coating. The quartz portion is fluorescent, which is the quickest way to discover whether you have true Youngite. The Cotton Candy stone is not fluorescent, even though it often looks the same.
|Credit: Mike Nelson|
Unfortunately, the area where the Youngite was mined is reported to be mined out and the specific area is no longer open to the public. There are some pieces available, generally at a pretty high price point. If you're considering investing in some, I suggest you ask the seller for regular and short-wave pictures from the same angle to be sure you're getting the real deal.
When I described my Cotton Candy slab and told him I believed it came from Mexico, that explained a lot of the differences between the two similar rocks. Most of the agate in that part of Mexico comes from volcanic rocks like Retaliate nodules rather than sedimentary limestone like Youngite. The brecciated materials in both probably get their color from iron in them.
So, they really are very different rocks.
IN MY SHOP
|My finished cab from the slab above,|
You can see the pencil marks I made around the void that has the druzy coated botryoidal shapes and that I used to set the shape.
After I got it cut, shaped, and polished, you can see the yellow-looking matrix has become white with a touch of blue tinge. The peachy material has finished out as pink and there are obvious bands around the void and the pink. It took a lot of scrubbing to clean the interior shapes, but it was worth it.
|My Youngite cab|
I had purchased a small slab of Youngite years ago without knowing what it was, and made a cabochon with it. How do I know it's Youngite and not Cotton Candy? It's fluorescent!
Youngite contains chalcedony and quartz, so it fluoresces mostly green. I tried my teardrop cab above under the long and short wave lights, but nada. That was a real surprise since the botryoidal formations inside the vug appear to be quartz druzy, but they obviously aren't.
To see how Youngite lights up, check out the image on Mindat.org at Click Here.
Also, when you look at the two cabs, you'll notice how very similar they are. But, a very close examination of their mineral components shows that they are not the same thing at all. Sort of like green gemmy faceted stones. Are they apatite Ca5(PO4)3(Cl/F/OH) or are they emeralds
Be3Al2(Si6O18)? The only way to know for sure is to consult a gemologist.
From a lapidary standpoint, I feel that both materials are excellent lapidary material. They are nice to work with and take a beautiful polish. I would caution about what I noted earlier. Because of its current rarity, real Youngite commands a relatively high price in the market. Cotton Candy is commonly available. If you are considering a purchase, be careful you get what you pay for.
Until next time, I hope you find joy (and great rocks) through the holidays you celebrate this time of year.
Your Lapidary Whisperer,