Tuesday, March 5, 2019

GARNETS

Image credit: Wikipedia

 One of the fun things about doing this blog is that I often start it thinking the subject will be simple and I'll get through it in no time.  So . . .

Garnets, I thought! I'll do a blog post on garnets! I love them, I've seen them in a few different colors, and I've heard words like Grossular thrown around a lot. Should be a piece of cake, right? You already know the answer; it's not. 
Uvarovite Image: Wikipedia



First, garnet is more of a category than a specific gemstone. For identification, these six minerals are considered garnets:  pyrope, almandine, spessartine, grossular, uvariote and andradite.   All of the species have similar crystal forms as well as physical properties, but they contain different chemicals.


MORE THAN A PRETTY FACE

Garnets are not only gemstones, they've also been used as abrasives since the Bronze Age. Really!  If you go by any place that sells sand paper or other abrasives, you'll see that garnet is used on products in a wide range of grits. Somehow, it seems sad to think gemstone and see sandpaper, but like other gemstones, garnet occurs in a range of qualities and not all are gemmy.

FUN FACTS

As gemstones, early in history, they were named "granatum" which meant pomegranate because the color of the stone resembled the color of the pomegranate seeds. 

Sometimes red garnets and other red gemstones, like ruby spinel, are collectively called carbuncles. Early Latin defined carbuncle as a burning coal. In medieval times a carbuncle was a stone with magical properties. It could create light in a dark place. According to Wikipedia, In the French romance of c.1150, a fictionalized Charlemagne finds that his bedchamber in Emperor Hugo's palace has such lighting. However, for people today, a carbuncle is more likely to be know as a cluster of boils in flesh cause by a staph infection. (No, I'm not putting a picture of that kind of carbuncle in my blog!)

File:Grossular garnet from Quebec, collected by Dr John Hunter in the 18th century, Hunterian Museum, Glasgow.jpg
Grossular garnet
BACK TO GROSSULAR

In my (limited) experience, any time a cluster of small garnet crystals is found together, it is referred to as grossular. Yet, as you undoubtedly noticed above, it is a specific kind of garnet. It comes in most colors except blue, but is most often green. In fact, it's name is a nod to the gooseberry's in Siberia which are the same color as the grossular garnets that are mined there.Yet, because it can come in many colors, my original understanding of the term may be more accurate than I thought.  Here's a golden specimen of grossular garnets that was collected by Dr. John Hunter in the 18th century.


WORKING ON GARNETS

For lapidary purposes, it helps to know that garnets can range from 6.5 to 7.5 on the Mohs scale.  Because of this, it can be cabbed and faceted. In some circumstances where they are not gemmy enough for jewelry, you can tumble them like I did here!  

This is a bunch of small grape garnets tumbled to help the color come through and put in a wine glass. Now, they are part of one of my rock meal cases as "grape wine".








MY GARNETS



I am one of those who really enjoy garnet jewelry, especially the reds and red/browns.  There's something both earthy and full of life about them.


This ring goes everywhere and always makes me smile.The warmth of the golden/red color is seriously classy without being too blingy.

And, of course, as a rockhound, I've managed to acquire a piece of rough rock that contains garnets.  It's pretty cool the way there are pockets all through the rock and the perfect garnets are nestled inside.







So, what is your favorite garnet and why? Drop me a note with a picture!

Take time while it's still show season to go out and find some yourself (maybe not as much fun as searching them out in nature, but easier and cleaner!).

To get the latest scheduling for rock shows around the country, go to Rock & Gem's website Here

Until next time, I'm your Lapidary Whisperer,

Donna

Tuesday, February 5, 2019

CHANNELING A NEW THOUGHT

CHANNELING A NEW THOUGHT

Perhaps some of you remember my post in January 2018 about Channels in  Geodes and whether those channels brought material into the geode being formed or drained material out.   It was a lot of fun to research and I got some really good answers. But maybe not all the best ones . . .

Unfortunately, I went about my research in a less-than-scientific manner beginning with a false belief that since I'd seen and photographed those channels in some geodes, they must have or previously had similar channels in all geodes.

Oops.


Last week I was thumbing through some older Rock & Gem Magazines and found the accurate information,pop right up in front of me. In the June 2016 issue, an article by Marcos Campos-Venuti titled, Big Band Theory: A New Explanation of Band Formation in Nodular Agates.

Campos-Venuti wrote, "A connective channel is also a primary structure and has not been formed by deformation of the bands. This channel is simply a small interruption of the and where water flowed quickly into the cavity as opposed to seeping slowly through the porous first chalcedony layer.

"For that reason, the terms "outflow channel and "inflow channel" are wrong and result from the erroneous perception that the channel was formed by deformation of the bands from the inside to the inside or vice versa." The mineral-rich water seeps into the hollow area during wet seasons when it is submerged. When the dry season arrives, the water/liquid thickens and adheres to the inside of the geode in bands of chalcedony.

One of the causes of horizontal layers of chalcedony inside a geode can be caused by a slow drying process. When that happens, material can be dripped from the top as (sometimes causing stalactites), settling into flat layers on the bottom.

The channels themselves are caused by a weakness or crack in the outer layer of the the geode as it forms. That crack increases the flow of the fluid and can create layers that seem to create a balloon shape rather than a round  one with the balloon opening being the channel itself.


It's pretty easy to see the channel on the right side because of the staining. Chalcedony wasn't the only material that seeped into this geode.

After looking at countless geode images that have inclusions, I believe this cutie contains crystals of sphalerite, It's mineral composition is (Zn,Fe)S or zinc sulfide. The iron in it led to the staining at the opening of the channel and the crystal surfaces after the geode was opened to the air.


BEST LAID PLANS

In last month's blog, I was planning ahead for a fun trip to Tucson and Quartzsite and all the new material that was waiting there for me to rescue it and bring it home so we could get to know each other in my little shop.

As the poet Robert Burns wrote back in 1785, The best laid schemes of Mice and Men oft go awry, And leaves us nothing but grief and pain, For promised joy! 

I don't know how he knew I'd take a bad fall in late January that would knock off the top of my tibia and crack the bone the long way, but I agree with Burns' comment on the grief and pain!  I may even still be looking at surgery, so I'm VERY unhappily cancelling all my arrangements. There's just no way I can safely handle the jostling crowds this year much less carry or cart my finds back to my vehicle.  I'd been especially hoping to find some gemmy dino bone for cabbing at decent prices,

Darn.

I hope all of you who manage to go have amazing experiences and find your dream rocks in Arizona this winter.Here's hoping for better luck for me next year.

WHAT DID YOU FIND?


Send me pictures of your favorite find this winter in Arizona and I'll try to use them in a future blog post. Please send them directly to Donna@LapidaryWhisperer.com

Until next time, your Lapidary Whisperer,

Donna





Saturday, January 5, 2019

Petrified Palm - Two Views

 

* News about Tucson and Rock & Gem at the bottom of this post.
 
If someone tells you they have Petrified Palm, the first question is where from?  I don't mean Madagascar or Louisiana. I'm asking you whether it is from the trunk or roots.

The trunk slices tend to be very plain with small nearly identical markings evenly displayed. These are remnants of the rod-like structure that forms palms. I confess I tend to find petrified palm trunk a bit boring. I like rocks that talk to me and tell me their stories. This reminds me of a cat taking a nap. It's just there, not doing much of anything.
 
Here's my proof.



Years ago at our club show, my rock club had this massive ugly rock they were trying to sell. Nobody wanted anything to do with it. I finally made a ridiculously low offer and it was mine. I suspect because then they wouldn't have to drag it out of there. I would.
  

 


I took it to the shop where I had access to a large saw and cut it in half. It is palm. This is how the cut edge looks. It now rests in my yard under a redwood tree that keeps trying to cover it up with droppings. 


Admittedly, there are those who hold a different opinion. 


In Louisiana, they have declared petrified palm the state fossil. 

In Texas, they conveniently ignored biological reality and named "Petrified Palm Wood" the state stone in 1969.

Sorry, Texas. Palm is not really wood.

NOT WOOD?

I'm paraphrasing the detailed information from Han's Paleobotany Pages. Click here. Palm does not conform to the definition of wood because wood tissue is formed by cambium. All deciduous trees have that cell layer which produces bark on the outside of the tree and wood on the inside. He gives amazing descriptions of how they are different and I suggest you use the link above if you want to know more. I'm ready to go back to lapidary.

 
COME TO ME, MY PRETTIES . . . 

The other source of petrified palm--and to me the most interesting--is the root structure. The first time I saw petrified palm root, the colors and movement made me think it was crazy lace; but it really wasn't. It had a riot of colors but with no discernible pattern like you find in crazy lace. What it really looked like was a bunch of colorful worms writhing around happily together. Sometimes it looked like a long tube, others looked like the end of a pipe agate, and then there was sky blue quartz filling in the spaces between. 

Depending on where you are in the world, the petrified palm roots will have colors they have absorbed from the fossilizing process and the patterns will also reflect the kind of palm it was.

For example, lapidary artist Sue Gallagher (Rockhound Dog Designs) shared this picture of palm root she has that hailed from Malaysia.  You can clearly see the root writhing effect where the two colors meet.



 


 Jason Brousseau (NM Stone Supply on Facebook and instagram)shared this picture of a cab he made with petrified palm root, As you can see, it makes an amazingly dramatic piece! 





FROM A LAPIDARY STANDPOINT

Petrified palm is a chalcedony and clocks in at about 7.5 on the Mohs scale. That means it will take a fabulous shine. In fact, when I'm in Tucson this year I'm going to be looking especially for this. If you want to see a wider range of the looks of Palm Root, check out the RockhoundUSA site where the material is compared to Dali Paintings : Click Here

SPEAKING OF TUCSON

Make your trip to Tucson and Quartzsite this year better than ever by checking out some wonderful places to see and collect. Check out my article, Eyes on Arizona: Road Trip, in the January 2019 Rock & Gem Magazine. 



 Not a current subscriber? The magazine has recently had an editorial update and the articles and pictures are better than ever! You can subscribe at: http://www.rockngem.com/ 

 I'd love to see what lapidary creations you've crafted with Palm. Send me your images and comments to Donna@LapidaryWhisperer.com 

Until next time, I'm your Lapidary Whisperer,

Donna