Friday, July 5, 2019

MARIPOSITE - LAPIDARY WORTHY?

My Mariposite yard rock.

The green and white that make up Mariposite make it an attractive yard rock. But as they say in the television commercials, there's MORE!

WHAT'S IN A NAME?

When miners during the California Gold Rush discovered they could find gold and placer gold in the green and white rocks around them instead of standing in a cold creek with a pan, they named the rocks Mariposite for the town they were standing in. (Not a huge imagination happening here, but a great way to tell others where to find it).


It can be found in many areas around the world, where it is mostly called Mariposite, except for Canada where they call it Virginite for some reason. Now, if you want to check my research, please check for Virginite on Google. When I checked on Bing, their articles under "virginite" were not about rocks. Nuf said.

WHAT IS MARIPOSITE?

It's actually not a mineral. Depending on how you want to think about it, it's either a metamorphic rock or a conglomerate. Chromium-rich Mica give the rock its green color and its flash. Dolomite Marble or Quartz provide the matrix. 

Mariposite slab



CAN I CAB IT?

 That depends on your willingness to handle disappointment. First, let's examine the hardness on the Mohs scale of the mineral which compromise the rock

Mica       2.5-3 
Dolomitic Marble  3.5-4
Quartz  7

As you can see, the Mica and Marble are similar in hardness, but soft as heck. If you want to cab it, plan on making it into a pendant where the edges are encased or it won't last long.  When the Mica is next to Quartz, undercutting is a real problem. 

I decided to create some Mariposite flowers for this blog post. Not my best idea ever. You can see that  I got one (of several tried) flowers. The plan was to make three and make a divot in the center that would hold a crushed yellow rock/epoxy mix to make it look like a flower. 

Flower start in Mariposite 


The first one came out fine. A bit rustic, but that was what I was looking for.  The others, even though I was using 220 grit and higher, shattered. Apparently, this rock is known for, basically, falling apart. I plan to try to get some more done so I can make a flower arrangement, but I think I'll need to drop them on the floor first to see where the slab breaks naturally.

OTHER USES

Aside from gold mining and cabs, Mariposite has traditionally been used for other practical purposes including being a facing stone for buildings or fireplaces and even markers in cemeteries (although I suspect they weathered so quickly that their messages were soon lost).

Have you worked with Mariposite?  What was your reaction?

Until next time, your Lapidary Whisperer,

Donna








 

Wednesday, June 5, 2019

Onyx or Not?

Green striped Onyx lapidary slab
When I was thinking about a topic for this post, I noticed a slab of onyx on my worktable. The pastel green layers were beautiful, and still are, but now I know it's not really onyx.

Darn.

It's still a lovely material, but it's one of those situations where it's a lot catchier to call a mineral Onyx, than Banded Calcite.

The banded calcite, CaCO3, is a carbon-based mineral that is commonly found in Mexico and India. From a lapidary standpoint, it's pretty soft at around 3 on the Mohs Scale. 




POPULAR DECORATIVE MATERIAL

Onyx bowl in browns






Like me, you may have a bowl, carving, or chess set made with this soft stone. The softness of this material also means when you start working it on your grinding wheels, it is best to start with your second wheel in so you don't take off too much material too quickly.








Mindat.org Onyx image




 TRUE ONXY is actually a variety of Agate, and as such, hits the Mohs scale between 6.5 and 7, making it more than twice as hard as banded calcite. According to Mindat.org, Onyx is a black and white banded agate or at times a monochromatic agate with light and dark bands. It does come in brown and red varieties; they are called Sardonyx. Mindat states, "Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands." The stones with parallel bands have been used to make cameos.


Now, bear with me.  In the Mindat.org image, I would have just called this banded agate even though the brown layers are somewhat translucent. They are parallel, but also curved.  Of course, translucence is not a requirement of Onyx. In fact, it seems to rule the material out.
Wikipedia Onyx image


Now, the more I get into this, the stranger it seems. Here's another image from Wikipedia they claim is onyx. 















Limestone Onxy
According to Mindat.org, there are a lot of stones called onyx, like this limestone onyx(CaCO3).

Checking around the internet, I found claims of green onyx (can be one of several items), onyx opal, rhodochrosite onyx and more. It seems as if any mineral that is translucent is being labeled onyx. 



GETTING REAL

Under the theory that "IT IS WHATEVER I SAY IT IS" I hereby declare that in America, Onyx is a translucent calcite. It is very soft. It has layers, most often parallel, and comes in a wide range of mostly pastel colors. The GIA might disagree with my declaration, but since they don't include Onyx as a gemstone in their online Gem Encyclopedia, well, my decision stands. 

WORKING THE SLAB



The slab at the top is the one that inspired me to do a blog on Onyx. So, of course, I had to work on some of it. 

I know the picture makes it look somewhat cylindrical, but it's not. I cut across the light bands and domed it, making the straight lines look like they are curved. From one side to the other, the back is flat. I played around with the top so that it is flattened in a way that mimics the curve in the rock making the picture a bit of an optical illusion. Then I put a bevel all around the back edge to keep the material from chipping.

Fun stuff!







I'd love to hear what you think on this topic. 

Until next time,

Your Lapidary Whisperer,

 Donna
 









Finely Banded Black & White Onyx

Sunday, May 5, 2019

CRAZY FOR CARNELIAN


 As you read this blog post on carnelian, you may think back to my recent post on garnets. I'm not focusing so much on brown/red/gold rocks as much as I am fascinated in the way they both handle light.

Carnelian is a 7 on the Mohs scale; garnets are about the same at 6.5 to 7.5, so you'd think that they'd be about the same to polish. Not always.

There is some variation within the scale. For example, the cab on the cotton candy slab just refused to take a real shine (it's photographed wet), yet the cab I made with some lower-value carnelian that is infused with what I've heard called "corn flakes", takes a great polish--except where the cornflakes surface.

Carnelian with "Corn Flake" inclusions
While I'm continuing to explore better ways to get this particular piece of carnelian to take a nice polish, I love working with it because of the stripes and the quartz on top.  It appears that at one time the quartz on top  had shiny crystals. Weathering damaged them to the point that the top was mushy-looking. They were, however, tight enough that when I ground them down a bit they make an interesting top with flashes.

Carnelian is something I'd decided to do a post on, and kept putting aside. For starters, the only carnelian I had was not all that exciting, except for one piece with quartz crystals on top. I've probably looked at it a million times. I'd love to take the "V" on the right side and make it like a heart with a crystal top, but the quartz crystals on the right are more weathered and smooshed than the ones on the other side of the dip. Any of you readers have ideas for me?


Then my husband and I took a weekend trip to Northern California and scheduled a stop at Chapman's Gem & Mineral Shop in Fortuna, CA. This place has so much rough, any lapidary artist would give their eye teeth to have it in their back yard. I'd give you a link, but they don't seem to have their own web site, everyone else is too eager to promote them.  In the yard, I came across a barrel that simply said, "Brazilian Agate". I was expecting the colorful, layered agate I've often seen at shows.

Nope, this huge space was full of carnelian. Now, carnelian and agate are chalcedony.When I first saw the sign, I expected the Brazilian agates that have layers of colors, but I was very happy to find this wonderful material.

It is believed that carnelian was originally named after the color of the kornel cherry. It comes in colors ranging from brownish red to orange and can vary from translucent to opaque. Like garnets, the specimens that are mined are often heat treated to bring out their best colors. Here in the U.S., carnelian is found in Oregon and New Jersey. Along with Brazil, where my latest rough was mined, it is found in Uruguay and India.


This carved Carnelian hook shows what a talented lapidary artist can do. It was fashioned by Stephan Roess artist, (stephan.roess@gmail.com).

This is a slab I cut from one of the pieces of rough I purchased at Chapman's. The fortifications where the agate bands suddenly change angle give it a lot of personality. I haven't worked it yet. It keeps smiling at me and as the Lapidary Whisperer, I listen to my stones and this one seems happy just the way it is!
Carnelian slab with Happy Face






Here's another slab quartz/carnelian with fortifications. It hasn't told me what it wants to be yet, but I have my eyes on it.


Until next time, I'm your Lapidary Whisperer,

Donna






Friday, April 5, 2019

Ocean Jasper

Image courtesy of Enter the Earth

Every time I see Ocean Jasper, I'm amazed at the colors and patterns. 

I became very curious about this delightful lapidary material. Thinking it was so well-known in the lapidary world that there would be a wealth of information available from a variety of sources (mindat.org, you disappointed me). I found myself doing my initial research at Enter the Earth.

The first thing I learned is that rather than being a general description of a multi-colored stone that typically features spheres and may include banding and/or druzy, Ocean Jasper® is a registered trademark owned by the Gem Shop.

Image courtesy of Enter the Earth


FUN FACT: This material that is only found on the Northwestern side of the Island of Madagascar, which, at 228,900 square miles, low off the eastern shore of southern Africa.  It is the world's fourth-largest island. Many of us know of  as the supplier of 80% of the world's natural vanilla.


Ocean Jasper is not mined from the ocean, but close.  Paul Obeniche had seen references to the material in a 1977 photo of Kabamby Ocean Jasper which was included in Grund’s Encyclop√©die des Min√©raux (French, “Encyclopedia of Minerals”). 

 Years later when  a prospector brought him samples, Obeniche set out to prospect for it himself. He found it in October 1999 in northwestern Madagascar when low tide made the veins visible. The material was underground and as prospecting advanced, each additional vein has been found further inland.
 
When you find Ocean Jasper at a show or online, it came from Enter the Earth which owns the mines. Obeniche, who discovered the deposits, mentored Nadar Kawar who now owns the mine.

FUN FACT: It was first introduced to rockhounds and lapidary artists at the Tucson Show in 2000.
 
Image courtesy of Enter the Earth
When asked about the availability of the material, Chris Matthews, spokesperson for Enter the Earth, says,  "We never know how much Ocean Jasper is going to be available.  Some years there is none.  For example, we had no new rough from 2006-2013.  The vast majority of what is found is lower quality, with little to no color and patterning.  Since we only import the "A" and "B" quality rough and polished materials, Ocean Jasper may be limited, even when being actively mined. Speaking for lapidaries everywhere, I hope they find an endless vein of the best stuff this year!

"While we have not found anything large enough to be called another "vein", we have hit a few larger pockets of rough since 2014.  The most recent one is very dark green, with light yellow and white banding, and the previous one was more muted, mostly blueish green, yellowish green, and gray." They continue to search for more veins and pockets.



NOT OCEAN JASPER

There are many kinds of orbicular jasper in the world, but the trademarked Ocean Jasper is found only in Madagascar.

Kambaba jasper, green and dark, is also found in Madagascar, but it is not Ocean Jasper.
 

 Other orbicular jaspers I've seen have been distinctly different enough to easily differentiate them from the Ocean Jasper material such as this piece of Morgan Hill Poppy Jasper.







VIEW FROM THE LAPIDARY SHOP

My Ocean Jasper!
While my experience with Ocean Jasper is somewhat limited, I love this material. In addition to telling stories with its orbs and patterns, it has two of my favorite characteristics: it is stable and contains druzy-lined vugs. 

I bet that you, like me, have worked with material that contains orbs of one sort or another and found that when you were busy trying to craft a shape and polish it, that many of the little orbs were busy jumping ship, leaving you with small, spherical holes. Not the look you were hoping for. I haven't had this problem with Ocean Jasper.


As your Lapidary Whisperer, you know I'm always looking for the story in the stone. Druzy-lined vugs are perfect for giving a cabochon character. For example, this is one of my Ocean Jasper cabs.  I absolutely love the shiny dark green druzy that lurks like a hidden forest in this Ocean Jasper cab I made.


I've found that the pieces and slabs of this jasper take a very nice shine, always a good thing in my book!

Depending on the vendor you shop with, Ocean Jasper can be a bit dear, but it's absolutely worth it. It's for sale at the Enter the Earth site, some other vendors and at shows. I've mostly seen it priced by the slab or by the pound (when I see prices by the gram, it tends to scare me away). 

I'd love to see what you've done with the Ocean Jasper you have. Send me an image at Donna@LapidaryWhisperer.com

Next time, let's talk about carnelian, the mineral named after a fruit!

Until then,

Your Lapidary Whisperer,

Donna

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