Friday, October 5, 2018

Colorful Moss and a Mossy Surprise!

As my regular readers know, I love listening to the stories the rocks tell me! If you're looking for a category of rocks that are especially chatty, you can't beat those we call "mossy". There are others that love to tell stories, including rhyolite and dendritic rocks, and they're close behind. But nothing beats the storytelling talent of a mossy rock.

You may have noticed I consider mossy rocks and dendritic ones to be different items although some people use the terms interchangeably. For details about how they differ, see my previous blog post "Thanksgiving with Dendrites."


 

I call this beauty "The Fire Swamp", because it reminds me of the scenes in the Princess Bride
movie where Westley and Buttercup fight their way through the Fire Swamp while trying to evade capture. As a bit of an aside, their major danger there was "rodents of unusual size" and now there is actually a documentary movie about huge swamp rats (nutria) infesting Louisiana titled Rodents of Unusual Size, check it out on IMDB.

TOTALLY ENCLOSED MOSS 

Like  the cab above, I've had the good fortune to work with some beautiful colorful ones from around the world, even if I don't always know where they came from. At the lapidary shop where I go every week, they'll often ask where I found a particular rock, and they're getting to expect my answer to be along the lines of "Tucson" or "the show last weekend" instead of some prospecting site. This delightful mossy agate is keeping its secrets so far, When it finally tells me what it wants to look like, I'm all in!



This cab is made from fully-enclosed moss in a clear quartz matrix and I'm pretty sure I know where it's from. This is from a slab of Regency Rose Graveyard Point Agate from the Owyhee Mountains in Oregon. This one told me it felt like fire and smoke and that's the story I tried to show when I made this cab.










This is very different kind of mossy agate. This one has a name I'd never have guessed from looking at it. It's Stinking Water Plume Agate!  That name would seem to fit better on the "Fire Swamp" at the top.  This material has a delightful snowstorm story and it hails from Stinking Water Pass in Oregon and I've only seen it available at a show once. Grab it if you see some. It makes the most beautiful winter-scene cabs!





SURPRISE!  MOSS OUTSIDE THE ROCK!

I cut this bubbly beauty off the edge of a piece of Regency Red Ghost Graveyard Plume Agate. The way this happens is the plumes actually form first and then over time they are surrounded by agate. In my experience, many pieces can be sliced and often take a wonderful polish if they are solid enough.  This one seems to be showing me a wildfire with strong winds. Or, it could just be that I live in Northern California and this has been a horrific year for wildfires. What do you see?


This whole slab is less than four inches long. I love the imaginary mouth complete with quartz crystal teeth and the red lines. The lines themselves are only about as thick as a sewing thread, and they have teeny-tiny quartz crystals coating them like a blanket.

I photographed this one wet because the red lines look so fragile and the white bits matrix are nothing more than a collection of bubble-like material, that I'm afraid this one might not make it through the polishing stage, so I'm keeping it as a specimen.



Admit it, this one looks like a snail on its way off the page! At less than three inches long, it is one I love to look at. Theoretically, I could cut off the last third to make a cab. The other side has several interesting small vugs lined with biotryoidal quartz, but I'd sure miss my snail!






Has a rock told you as story lately?  Send me a picture of the rock and the story it told you. Maybe I can use it in a future blog post.

Until next time, I'm you Lapidary Whisperer,

Donna

Wednesday, September 5, 2018

THERE'S A TIFFANY STONE - AND IT'S NOT A DIAMOND

   When I first heard of Tiffany Stone, I expected it to be a soft, cool aqua, like the Tiffany Jewelry boxes; Pantone 1837 for those of you who, like me, love side trips when you're doing research. The color number refers to the year that Tiffany & Co. was founded. That wasn't the color. It's purple!

Tiffany Stone is also the name of an actress known for her work in A Very Harold & Kumar 3D Christmas.

 

Enough trivia. Back to the important stuff, rocks!

 

YUP, ROCKS

 

A lot of what I write about in my blog is committing lapidary on minerals, but Tiffany Stone is actually a rock. Here's the difference:

MINERAL: A mineral has a specific chemical composition and you will see the chemical formula for each mineral tells what the chemicals in the mineral are and their proportions. For example, the mineral Quartz is SiO2 which tells you it is made up of Si, or silicon, and oxygen. Some varieties, like Rose Quartz, have colors as a result of inclusions, but the inclusions don't change the formula. Usually, minerals each have a distinctive crystal formation that results from the atoms of their formula. For more details on how this works, Click Here

  

ROCK: Unlike minerals that always have the same formula, rocks are formed as an aggregate that includes more than one mineral. Rocks are not identified by their chemical formula, but by the way they are formed; Igneous (formed by fire), Metamorphic (changes over time), and Sedimentary (mineral or organic bits that have settled and hardened). Tiffany Stone is a sedimentary rock that is primarily fluorite with additions including opal, calcite, quartz, and others.

BEWARE

When you see some at a show or online and it's expensive, don't be surprised. The only place it is mined in the world is at the Brush Wellman beryllium mine at Spor Mountain in western Utah. If a vendor tries to tell you it is so expensive because it is imported from China or Africa, walk away. It's expensive because it's rare.

TIFFANY STONE ON THE LAPIDARY BENCH

I purchased my specimens at the Arizona shows in the winter.  I got two nice, but not remarkable, nodules.

When I sliced the first one, I noticed it was awfully soft. Depending on your source, it will run between 4-5.5 on the Mohs scale, and even at the top hardness it is a pretty soft stone. When you make cabochons with it, plan to mount them in protected settings (not rings) because it's very easy to scratch, ruining the surface finish.

One of the distinctive aspects of Tiffany Stone is the swirling pattern often found. It became a problem for me because my piece was so soft that a bit of it flaked off where the swirl met some different-colored material on my grinder wheel. I stopped right there and stabilized all my slabs before continuing any further.

I also realized that I could skip some of my wheels because of the softness.  I have a 50,000 grit wheel which normally makes anything shine, but I found it took cerium oxide on leather to get the best possible finish which was a luster more than a shine. 

WOULD I BUY IT AGAIN?

That's the question I ask myself when I'm working with a new material. I'm afraid my answer is that I probably won't. 

On the plus side, it's easy to work on (after I stabilized it).

On the minus side, it's expensive and doesn't take a real shine. My pieces are roughly the same color as amethyst/purple sage agate which is much harder and reliably takes a high shine.

Have you worked with this material?  If so, what was your impression?

I hope you enjoy my blog post. If you have any questions, let me know and I'll do my best to answer them. All the photos in this post were taken by me. They are available for a small fee. Please do not take and use them without permission--it's stealing. Thanks for supporting ethical behavior on the Web!

See you next time!

Your Lapidary Whisperer,

Donna

         found in beryllium ore found in beryllium ore

 


 

 

 




 

 

 

 

 








Home » Gemstones »



Tiffany Stone



Author: , Ph.D., GIA Graduate Gemologist

Tiffany Stone
A Tiffany Stone nodule, sliced in half and polished. Can you see why some people call it "ice cream stone"?   Public domain image by Scott Horvath, USGS.

What Is Tiffany Stone?

"Tiffany stone" is a trade name used for a purple, blue and white gem material that can be cut and polished into beautiful beads, cabochons and tumbled stones. Geologically, Tiffany stone is a rock composed primarily of fluorite with smaller amounts of opal, calcite, dolomite, quartz, chalcedony, bertrandite and other materials. Other names used for Tiffany stone are "opalized fluorite," "ice cream stone," and "bertrandite."
Tiffany Stone
Utah Tiffany Stone: "Tiffany Stone" is an unusual material found as mineralized nodules in a beryllium tuff at the site of the Brush-Wellman beryllium mine. It is thought to be an opalized fluorite. Tiffany Stone is also known as "bertrandite" and "ice cream opal." It is a rare material found only at the Brush-Wellman location.

Where Is Tiffany Stone Found?

Tiffany stone is a rare material. It is mined at one location worldwide - the Brush Wellman beryllium mine, at Spor Mountain, western Utah. It occurs there as nodules that are part of the ore produced at the mine. The nodules typically contain between one and two percent beryllium by weight.
The United States Geological Survey reports that the nodules are carbonate clasts that have been largely replaced by fluorite. Small amounts of bertrandite, a beryllium mineral with a chemical composition of Be4Si2O7(OH)2, occurs as submicroscopic grains within the fluorite.
Almost all of the Tiffany stone mined at Spor Mountain is crushed and used to produce beryllium. A small amount has been carried out of the mine by employees, and a small amount has been gathered by collectors who have rarely been allowed into the mine. These are the only sources of the gem material because Brush Wellman has always been interested in producing beryllium and has not been interested in Tiffany stone.

Other Names for Tiffany Stone

The most appropriate name for Tiffany stone is “opal fluorite” or “opalized fluorite.” These names reasonably represent the composition of most specimens. Another popular name is “bertrandite.” That name is incorrect because bertrandite is a mineral, which only comprises a few percent of the rock known as Tiffany stone. It is also called "ice cream stone" because of its delicious color.
There are numerous stories behind the name “Tiffany Stone.” Some people attribute the name to Tiffany and Company, the famous luxury goods retailer. The company has never been associated with the mine or with Tiffany stone. Others attribute the name to the daughter of a Brush Wellman employee who collected the colorful nodules brought home by her father. This story is possible, but the names of the miner or his daughter are not found in any written record.

Where Can You Buy Tiffany Stone?

Jewelry made with Tiffany stone is unlikely to be found in a mall jewelry store. Instead, it is most likely to be sold at a gem and mineral show, at a rock shop, or by a lapidarist at a craft show. You might also find it at an online craft marketplace such as Etsy. Some of these sellers are likely to be the same person who cut the stone and made the setting. You will rarely find that when buying diamonds, emeralds, rubies or sapphires!

About Using Tiffany Stone in Jewelry

Although Tiffany Stone can be very attractive, there is an important thing to consider when using in jewelry - it has a Mohs hardness of only 5 to 5 1/2. That makes it very easy to scratch. If Tiffany Stone is used in a ring, it will quickly show signs of wear and lose its nice polish and luster. For that reason, Tiffany Stone is best used in pendants, beads, earrings and other types of jewelry that will not be subjected to abrasion.
One thing about Tiffany Stone that will probably make you happy is its price. Even though it is very rare and quite beautiful, cabochons with beautiful color, pattern and size can usually be purchased for $75 or less. It also looks great in white metal. That allows it to be placed in a sterling silver setting, getting you the whole piece for a price of $150 or less.

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