Wednesday, January 17, 2018

The Unnatural Life of Created Cabochon Material




When I think of rocks for my lapidary projects, I tend to think of minerals in their natural state. When I think of lab-created mineral products, I think of gemstones like sapphire or diamond. But there is actually a third category that falls roughly between the two. The truly unnatural cab materials.

The way I see it, Ray Bridewell's home-grown crystals are at the top of the heap. They are bright and gemmy and take an amazing polish





I made this incredible free-form cabochon using material I purchased from Ray. He makes it by melting quartz and other materials to 2300 degrees Fahrenheit and letting the cool slowly over a period of weeks. As it cools, crystals bloom inside the new slab.




 This pink cabochon is made of the same basic material and as you can see the spikes are thicker and there is almost microscopic sparkling dots adding a completely different look to the finished cab.

I'm going to give him a plug because I love this material so much and so will you.  Contact him at
Bridewell Stone Studios, https://www.facebook.com/BridewellArt/
 to see what he has available now.










SLAG GLASS

Slag glass is a fascinating mix of manufactured (the glass) and the artistic patterns that are formed when it is dumped into a heap. It's not so much  a cold-blooded product like goldstone (see below), but a happy combination of the way the different colors are disposed of into a glass slag heap.

For me, this comes right under Roy's crystals because while it is pretty and shiny, it lacks the gemmy look of the other.

Slag glass is excess material from the glass making process. It is often cast aside as undesirable--unless of course, you love committing lapidary on it.

I found this yummy piece as a random slab at a rock show. I loved the movement it contained and decided to take it home and let it tell its story. You can clearly see some aspects of the rock supporting the cabochon through the transparent sections. 






 ALL THE STARS IN THE SKY - GOLDSTONE

You know when something is too good to be true . . . but it isn't?

Goldstone is often found at rockshows and in jewelry. I've been told at various times that it was mined in Russia or South America and that the flecks were real gold.

Image Credit: Wikipedia
Great story; but not true. If a seller tells you this, assume anything else they tell you about their merchandise is equally untrue.

However, it can also be truthfully called adventurine glass, stellaria, or monkstone.

It comes in two steps below Ray's crystals because of its uniform consistency. Ever notice the difference between a natural granite slab countertop and a manufactured one?  The natural one will generally have inconsistencies that pull your eye around the surface. The uniformity of the manufactured ones is lovely to look at, but without the inherent charm of the natural.

Goldstone is a glass product made in a low-oxygen environment. According to Wikipedia, "The most common form of goldstone is reddish-brown, containing tiny crystals of metallic copper that require special conditions to form properly. The initial batch is melted together from silica, copper oxide, and other metal oxides to chemically reduce the copper ions to elemental copper. The vat is then sealed off from the air and maintained within a narrow temperature range, keeping the glass hot enough to remain liquid while allowing metallic crystals to precipitate from solution without melting or oxidizing.

"After a suitable crystallization period, the entire batch is cooled to a single solid mass, which is then broken out of the vat for selection and shaping. The final appearance of each batch is highly variable and heterogenous. The best material is near the center or "heart" of the mass, ideally with large, bright metal crystals suspended in a semitransparent glass matrix."


START YOUR ENGINES!

As you know, most Fordite is a single color with swirls showing the way the material settled and hardened. Sometimes it's called Motor Agate because it is made by layers and layers of automobile paint that was sprayed at cars and has hardened to a product that can be cut and polished into cabochons.

This comes in last of the four lapidary materials covered in this blog post. It just doesn't have the pizazz of the others and isn't as likely to talk to me about what it wants to be as the others.

When I was in Quaratzsite  last year, I saw one block of Fordite that really caught my eye.  It consisted of the primary colors of red, blue and yellow. It was so cheerful that I just couldn't resist.

It's fun to work with and makes beautiful slabs and cabs (doesn't this one look almost like a button for a child's outfit?). But if you get some, be careful not to work it with too rough a grit.  If I used anything rougher than a 220 grit on my wheel, the little bits of color had a tendency to fly off.

I'd love to hear about any unnatural materials you use for cabbing. Drop me a note!

Until next time,
Your Lapidary Whisperer

Donna

Wednesday, January 3, 2018

GEODE CHANNELS--ARE THE MINERALS GOING IN OR OUT?




Have you ever seen what looks like a passageway between the inside and outside of a geode and wondered what is was?


 I love the colors and swirls of this geode and the way it shows the passage. It reminds me of the art work by Judy Chicago called "The Dinner Party".
Photo Credit, Dave Kleesattle. 



From the few I've seen, I always assumed the material was flowing in through the passage and coating the inside of the empty geode.  Then I heard a different theory.

ONE FASCINATING OPINION


Dave Kleesattle
Dave Kleesattle, a geologist and rockhound, did a program at the Contra Costa Mineral & Gem Society on what he had learned years ago to call Einflusskanalen (which translates from German as "Influence Channels".

His theory was that the channels were formed when the crystals formed inside the geode, thereby creating pressure on its walls. Then at a weak point on the wall, the pressure created an exit, reducing the inner pressure to a manageable level.

I understood where he was coming from, but that didn't explain situations like the one in this image below where you can plainly see that at some time, horizontal layers formed inside the geode. I was perplexed.






MY THEORY

Photo courtesy of Dave Kleesattle. 


Now, I've always suspected that the passage was from a crack or weak point that allowed mineral-saturated fluids to enter and over time the liquid evaporated, leaving space for the next layer to enter. In my theory, years when the mineral-rich water filled the open geode, it coated the interior walls. When there were years with lower quantities of water entering the geode, you got the horizontal layers. Notice in this geode that there are layers covering the irregular edges as well as a section of white and red horizontal layers.





TIME TO CALL IN THE EXPERT!


Brad Cross

To find the definitive answer to what the passages sometimes seen in geodes do, I called on Brad L. Cross, co-author of Geodes Nature's Treasures (Gem Guides Books, 2006)

He wrote, "It appears you have run into the same perplexing question that all of us “students of agates” have encountered, “Are these mysterious features we see in agates (and some geodes) an entrance or exit channel?”  I’ve been a serious agate collector/student for 45 years now and Donna, I simply don’t have a solid answer to your question.  I might add that I am far more than an “armchair collector,” I’ve conducted a tremendous amount of field research on various agate deposits and I find nothing that provides a concrete answer. 

Photo credit: Dave Kleesattle
"For years I felt that these “conduit channels” were an entrance point for mineralized fluids.  However, I can show you specimens where that channel never reaches the outer edge of the agate, highly suggesting it was an exit channel generated during crystallization of the agate.

My personal opinion is that we are likely seeing both entrance and exit channels.  One of the things that us agate students must always remember when we are looking at these features is that we are only seeing a surface or two-dimensional view.  The question arises,“What is the geometry of that tube deeper into the agate?”  While the view we have in hand shows the tube not reaching the outer rim or edge of the agate, it may very well reach the surface several millimeters deeper in the agate and we are simply not seeing it in the view we have in hand.                       

"I can assure you of one thing – the question of whether these are entrance or exit channels will continue until the end of time.  We do not have a solid answer today and unfortunately we’re not going to have an answer when you and I leave this ole earth.  Very little solid science or research has been conducted on agates – primarily because they have no economic value to industry.  No one wants to sink money into expensive research when there is no monetary return for their investment dollar.  That’s primarily why we have no solid answers today on these unusual features. 

Photo credit: Dave Kleesattle
"For now, simply enjoy these features in agates as a mystery we may never hold the answer to.  Perhaps it’s that unknown that makes agates and geodes so interesting and attractive.  IF we knew the answers to all of the questions these incredible specimens possess, they simply may not be as interesting and attractive to us."   







I'd like to thank Brad and Dave for the help they gave me with this blog post. Obviously, this is a fascinating topic, and barring amazing money for research on this topic, Brad's explanation is the best we'll ever have.

 SHAMELESS PLUG

I purchased Brad's "Geodes: Nature's Treasures" at a rock show. While it doesn't discuss the channels I've been exploring in this edition of my blog, it is a comprehensive guide to all things relating to geodes. The pictures of remarkable geodes like I've never seen before are well worth the price of the book alone.

If you're interested, contact GEM GUIDES BOOKS  at www.gemguidesbooks.com or order them on Amazon.com


Until next time, when I'm writing about The Unnatural Life of Created Cabochon Material,

Your Lapidary Whisperer,

Donna