Jeff R Graham shares his opinions on various topics in Just Ask Jeff. See what his thoughts are on Schiller/Oregon Sunstone.
13 Minute Read
Oregon Sunstone comes in many varieties. Colors, color with schiller, copper schiller and champagne.
Left: One of the prettiest types of schiller Sunstone in my opinion. As you can see this piece is a copper schiller spot surrounded by a very nice green halo. This is fairly rare and a top grade specimen.
Here is an article on Sunstone Grading and types.
In this article I am going to be talking about Oregon copper schiller Sunstone. Color/copper schiller Sunstone also fits in these basic ideas I will be discussing in this article. Mainly because the schiller is often found in the colored areas of colored Sunstone.
Note: These observations are on Oregon Sunstone and while some of the basics may apply to Sunstone and Feldspar from other origins (India, Tanzania, et...) the Oregon material is pretty unique and should not be confused with other locations. Also man-made colors like much of the Andesine stones on the market are not natural and do not fit these observations. Oregon material is completely natural and has no known treatments.
There are some very basic things about Oregon schiller Sunstone that frankly I have never seen anyone mention and I have certainly never seen anything written about the phenomenon's I am going to cover in this article. These are all my personal observations and conclusions from cutting and cleaning literally thousands of Sunstone's.
A little bit about how Sunstone occurs. Schiller in Oregon Sunstone is particles of suspended copper (in Indian and Tanzania material it is Hematite). These particles of schiller can be in many configurations including around, in and through spots of color. I have talked to many of the Sunstone miners and heard many theories about how the copper schiller and colors are formed. I am not a geologist and frankly I doubt that there is ever going to be much in the way of real proof about how exactly Sunstone forms.
But. The main theory I have heard and the one that sounds most logical to me is that the copper schiller is in solution as the Sunstone forms. The Sunstone is in "flows" like lava flows actually. As the copper ages and degrades it tends to oxidize and turn colors, the main one being copper/pink/red surrounded by green/teal. Which is what is called the watermelon color. Further down the road is copper/pink/red. There maybe other factors at work, such as heat that effect the process and different minerals, and chemical compositions that could and probably do effect the colors and variety of Sunstone.
Sunstone, of course is fairly diverse and different colors as well as different chemical make ups occur in different mining locations and "flows". So there is no one exact color or type even in the Oregon material, which is one of the reason that Sunstone is so interesting to work with.
Sunstone occurs in "flows", think of the flows like random layers that flowed across the land during the geological formation of the area. There can be several "flows" in one location or none at all (which is why it is called mining, not finding). The heat in a Sunstone "flow" does seem to effect the amount and maybe the color found in the material. The hotter the "flow" the less color the Sunstone generally has, clears are mostly "hot flows". So really the best colors come from "cool flows".
Note: One thing that has been proven with all the Andesine treatments is that copper can be added and/or modified by heating and treatments in some material (mostly Mexican yellow material to date). Here is an Andesine article, as of July 2008 no one has successfully treated Oregon Sunstone that I am aware of.
The copper schiller in Oregon Sunstone occurs in four simple types that I have personally observed and worked with. There maybe slight variations and there probably is, but these four types are fairly common in my experience. Here is what I have seen and my suggestions on how to work with the material, depending on the type.
Threads - This is a very striking formation and I personally find this type to be one of the prettiest and it makes outstanding polished cabs, and faceted stones.
To orientate this material.
Cabbing - In cabs it is best to orientate the the threads so that they are parallel to the table. Put the threads in the middle of the stone if you can, although this is not critical. The more towards the middle of the stone the threads are the better they will show up. Also you want the threads as parallel to the top and bottom of the stone as you can get them, this increases the flash of the threads from all directions.
I always tend to leave a large very slightly domed top on this kind of cab, because the flatter dome shows the threads and their flashes much better than a high dome cab will.
Flat Lapping - Thread types of schiller are ideal with the threads positioned in the middle of the stone and parallel to the front and back face of the stone.
I try to polish the front and the back parallel to the threads. That way you can see the threads flash from both sides and the two faced polished surfaces allow maximum light to enter the stone. Cutting the faces close to the treads does help improve the flash, but be careful no to cut through the schiller, if you cut too far you can cut through the schiller and loose the entire stone.
Faceting - Orientation depends on this type of schiller, but for thread schiller that is open enough (this is very important) to allow light to pass through and be reflected.
I like to orientate it basically two ways, either put the threads parallel to the table in the middle or orientate the threads so they will reflect off the pavilion facets and multiply themselves in reflections. This assumes that there is enough clear space in between the threads to allow some light to pass into the pavilion. The parallel orientation is fairly simple. The reflection orientation is more difficult and will take some experimentation for most cutters, but it is well worth it.
Spots or Speckle - Spots are one of the more common types of both color schiller and copper schiller that occurs.
Spots often have both schiller and color in them and can be quite striking. See the picture at the start of the article to see color and copper schiller.
Spot types are very pretty and they offer some interesting and unique opportunities when cutting.
Note: The main difference between spots of schiller and clouds of schiller is that the spots tend to be both more directional and 2 dimension in size and shape.
In other words the spots look like spots. They are not usually that deep and the schiller tends to have a single direction that it flashes in (from either side of the spot at 90 degrees). Clouds are more three dimensional and usually are like a cloud shape.
There can be some cross over in the cloud and spot types, but generally it is fairly easy to distinguish between the two types. Clouds have much more vague borders and tend to be larger schiller particles as well as flash differently and much more copper.
To orientate this material.
Cabbing - In cabs it is best to orientate the flash of the schiller/spot so it is parallel to the table or the top of the cab dome.
I prefer to make larger flatter slight domes because high domes cut through too much of the schiller and create a smaller flash.
Flat Lapping - These are ideal with the spots positioned in the middle of the stone and parallel to the front and back face of the stone.
I try to polish the front and the back parallel to the flash. That way you can see the schiller flash from both sides and the two faced polished surfaces allow maximum light to enter the stone. Depending on the stone it is possible to slightly dome both sides of the stone and some times a slight dome can increase the beauty of the stone by allowing more light as well as slightly different angles on the stone.
Orientate the flash of the schiller so that it is parallel to the table of the cuts. Also depending on the color spot and the amount of schiller, which varies other faceting designs will work quite well. I prefer simple reflector pavilions and checker tops. Depending on the depth of color a shallow or very deep stone design maybe used. Generally I pick a moderate depth design.
Sheets or Plates - This is a very interesting type of schiller. It is really fairly common in Sunstone material and makes interesting cut stones.
Note: The cleavage often runs in the same plane as the sheets of schiller. and you can tell the cleavage plane directions by looking at the sheets of schiller. There are 2 active cleavages and 1 not active cleavage in Sunstone, that are usually not any problems when cutting.
The sheets of schiller tend to be copper color, but there are some times colors surrounding the sheets of schiller and they can be very striking if cut correctly.
Sheets of schiller are just what they sound like, sheets of copper schiller in usually a single plane (there can be layers like a deck of cards like in these pictures there are 2 basic sheet/layers) that flash when orientated perpendicular the the light.
Because the schiller is in sheets and generally sheets of schiller are quite solid. Note the sheets of copper schiller are usually fine grained and run parallel to each other if there is more than one sheet in the rough. Often the sheets are '"torn" looking and depending on the sizes and shapes some times this type of stone makes better carvings.
The sheets allow very little light to carry all the way through the stone. In most cases the sheets of schiller reflect the majority of the light. So basically this type of schiller material works best in cabs and flat lapping, but it is possible to create attractive faceted stones. Generally when faceting sheet schiller I use reflective cuts like dutch and rose cuts as well as bead cuts.
To orientate this material.
Cabbing - In cabs it is best to orientate the the sheets so that the best flash is face up and on this type of material it is ideal for low or very slight domes.
As I said earlier, often sheets of schiller make very good carving material, because the sheets can be carved out sand around. Carving like this opens up the rough/stone and can often add more light and reflection.
Note: All Sunstone is really an ideal carving material and a very good choice for novice carvers to work with because it is not as hard as Quartz and many other materials, which make it easier to work with and polish. Of course I would recommend that novice carvers learn on the more inexpensive champagne (yellow) colored material which is available in nice sizes inexpensively.
Note: Be sure and also polish the backs of the cabs it make a better looking finished cab as well as letting some extra light in the cab
Flat Lapping - These are ideal with the layers positioned in the middle of the stone and parallel to the front and back face of the stone. I try to polish the front and the back parallel to the sheets. Sheets of schiller must be cut and polished pretty flat and parallel. Because the sheets of schiller are usually formed in a fairly flat plane and any dome or curve will often cut into or through the schiller layers. I find that the flatter I cut the table parallel to the sheet of schiller the better the stone and schiller look. The flash is interesting.
Faceting - This type of stone is ideal for rose cuts or cuts like Chick and Pillow. Orientate the flash of the schiller so that it is parallel to the table of the cuts. Use a flat or very low dome design on this kind of stone. Some of my Mirage cuts will work well in schiller. Remember that in the case of this type of schiller you are cutting to show the schiller not reflections.
Clouds - This is a very interesting type of schiller.
Clouds of schiller (1 way, 2 way, 3 way, 4 way is very rae) are really not all that common and the main thing when identifying clouds of schiller is... the the schiller looks like clouds. There is no real structure or layers, just a general cloud of usually large schiller copper particles.
This type of schiller is often multi directional in a cloud and the flash will often show from several directions.
Usually there are two or three directions that have the strongest flash. But there generally will not be any specific shape to the formation of the copper schiller. The best way to figure out the flash it to examine the material with a 100 watt light bulb and directly above your head as you look down on the stone from directly above the rough. Move the rough around under the light and use a sharpie ink marker to mark the direction of the best flash under the light.
To orientate this material.
Cabbing - In cabs it is best to orientate the the clouds so that the best flash is face up, or as face up as you can orientate the flash of the cloud. Cloud types of schiller material is ideal for high dome cabs and is probably about the best cabbing of all Sunstone, as lo the most well known. If possible orientate the flash or multiple flashes so they are all facing towards the top of the cab. Be sure and also polish the backs of the cabs.
Flat Lapping - These can be flat lapped but they are really better as cabs or faceted beads. Flat lap the flashes parallel to the tables or the top of the cab.
Note: This material is very nice carving and is great for many designs because the clouds of schiller are often multi-directional and well as pretty easy to work with. Clouds of schiller lend themselves to carving and are usually less sensitive to orientation when carving than most other types of Sunstone.
Faceting - This material is ideal for beads. Orientate the flash so that it shows best in whatever direction the bead will be viewed in. This type of stone is ideal for rose cuts or cuts like Chick and Pillow. Orientate the flash of the schiller so that it is parallel to the table of the cuts.
There are some other possible types if schiller, but I think that in most cases that if people examine their rough they will easily be able to spot the four basic types if schiller that I have identified in this article.
Knowing what kind of schiller you have in your rough will go a long ways towards helping most cutters in deciding how to cut the material. Follow my basic advice and I think that in most cases people will be very happy with the stones they cut.
I encourage people that have never cut Oregon Sunstone to try some... Oregon Sunstone if not only very unique in location as well as beauty, it is really a lot of fun to cut.
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