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Showing posts with label Sunstone. Show all posts
Showing posts with label Sunstone. Show all posts

Monday, October 25, 2010

Wire-Wrapped Agate Necklace and Earring Set !

While walking around in a field or climbing a mountain side, finding a great chunk of Agate or a piece of Jasper is a thrill for any rockhound, but being able to identify exactly what it is that has been found is quite a headache for the beginner. These headaches can be relieved very easily though with just a little bit of knowledge about the different Quartz group of stones. Agate and Jasper are actually Chalcedony, which in turn is cryptocrystalline Quartz. When you pick up a stone you can rule out that it is a piece of regular massive Quartz quite quickly just by looking to see if you can see grains within the stone. If you can see grains, you do not have an Agate or a Jasper. Most likely, what you have then is massive Quartz or some other type of stone. Many new rockhounds will mistake massive Quartz for a piece of Agate, so don't feel bad if you do. It's a very frequent mistake.
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Jasper and Agate will appear to be made of wax. If the rock is just plain clear to white translucent with no markings or patterns, it is considered Chalcedony. If it is opaque, that is, if you cannot see into or through it, it is Jasper. Jasper is most frequently earth tones or red but you can find jasper in just about any color or color combination and it can contain some very lively patterns. One well known form of Jasper is called 'Picture Jasper', and just as the name suggests, the lines and markings look just like a scenic picture of mountains and valleys or forests and so on. Geometric patterns are also common in Jasper stones.
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If a stone is an Agate, it will be translucent as is Chalcedony, but an Agate will have patterns. Most commonly, Agates have bands, and are appropriately called 'Banded Agate'. Sometimes the bands are also translucent, sometimes some are opaque. There are many Agates named to describe how they look, such as plume, orbicular, or flower and many that are named for the place they are found, such as Dryhead or Lake Superior.
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This design incorporates a very interesting piece of Agate, which is striped but also is considered partially a Fire Agate and a Druzy Agate and has been enclosed in a silver wire wrapped holder and bail. The necklace then contains puff oval Citrine beads and faceted round Sunstone beads with their "shiller" effect and highlighted with silver beads and finished with a Toggle Clasp. Matching silver French Hook earrings containing a faceted Sunstone bead completes the set.
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AGATE is a microcrystalline variety of quartz, chiefly chalcedony, characterised by its fineness of grain and brightness of color. Although Agates may be found in various kinds of rock, they are classically associated with volcanic rocks but can be common in certain metamorphic rocks. No gemstone is more creatively striped by Nature than Agate, the chalcedony quartz that forms in concentric layers in a wide variety of colours and textures. Each individual Agate forms by filling a cavity in host rock. As a result, Agate is often found as a round nodule, with concentric bands like the rings of a tree trunk. The bands sometimes look like eyes, fanciful scallops, or even a landscape with trees.
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CITRINE is any quartz crystal or cluster that is yellow or orange in color. Although often cut as a gemstone, Citrine is actually somewhat rare in nature. Most Citrines on the market have been heat treated. Specimens of low grade, inexpensive Amethyst or Smoky Quartz are often cooked at high temperatures to produce the more profitable orange yellow Citrine. Citrines whose colors have been produced by artificial means tend to have much more of an orange or reddish caste than those found in nature, which are usually a pale yellow. Much of the natural Citrine may have started out as Amethyst but heat from nearby magmatic bodies may have caused the change to Citrine. Citrine made by heating Amethyst may be returned to a purple color by bombarding it with beta radiation.
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SUNSTONE is a plagioclase feldspar, which when viewed from certain directions exhibits a spangeled appearance; this has led to its use as a gemstone. It has been found in Southern Norway, and in some United States localities. It is the official gemstone of Oregon. The optical effect appears to be due to reflections from enclosures of red hematite, in the form of minute scales, which are hexagonal, rhombic or irregular in shape, and are disposed parallel to the principal clevage-plane. These enclosures give the stone an appearance something like that of Aventurine, whence sunstone is known also as "aventurine-feldspar." The optical effect called "shiller" and the color in Oregon Sunstone is due to copper. In the middle part of this crystal, it sparks a lot, and usually has a dark color in the middle, and the color becomes lighter as it becomes the outer part.
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Saturday, August 1, 2009

Oregon's "Sunstone" !

The 1987 Legislature designated the Oregon Sunstone as the official state gemstone. Uncommon in its composition, clarity, and colors, it is a large, brightly colored transparent gem in the Feldspar family. The Oregon Sunstone attracts collectors and miners and has been identified as a boon to tourism and economic development in southeastern Oregon counties.
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A few years earlier, in 1965, the Thunder-egg (geode) was named state rock by the Legislature after rockhounds throughout Oregon voted it as their first choice. Thundereggs range in diameter from less than one inch to over four feet. Nondescript on the outside, they reveal exquisite designs in a wide range of colors when cut and polished. They are found chiefly in Crook, Jefferson, Malheur, Wasco and Wheeler counties.
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Oregon Sunstone is a Feldspar crystal formed as phenocrysts in molten lava and then discharged onto the surface of the earth by a volcano. As the lava weathers away or is broken up the crystals are released. While Feldspars are found all over the world, they are rarely gem grade. Central Oregon is one of the few places in the world where this type of Feldspar is found in gem grade and large enough to cut stones for jewelry. Sunstone is a plagioclase Feldspar exhibiting in certain directions a brilliant spangled appearance, which has led to its use as a gemstone. Oregon is the only place in the world where gem grade Sunstones are found containing copper. Varying amounts of copper cause the stones to range in color from water clear to yellow, as well as many shades of green, red and pink. Some stones contain from two to four of these colors. Some rare stones will even change colors in different light as Alexandrite does, and some are different colors when viewed from different directions (dichroic and trichroic)..
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In south central Oregon, northeast of Plush, the BLM has set aside 4 square miles for rock collectors to hunt for Sunstones. No claims can be filled within the BLM sunstone area, and there is no charge to prospect. Outside the BLM area, several major mines exist ihat are open to the public for digging and collecting. High Desert Gems & Minerals currently owns over 40 sunstone mining claims in the Plush and White Horse Ranch area of Oregon. One, the Spectrum Mine is a 20 acre patented mining claim located 27 miles northeast of Plush, Oregon. Another major mine in the area, the Dust Devil Mining Company, is Oregon’s premier Sunstone Fee-Digging venue where visitors can prospect virgin ground that has been opened with our heavy equipment – They are never limited to digging tailings or material that has already been high-graded. Visitors will take most of what they find FREE OF CHARGE, while certain very high-grade or collector stones will be charged at 25% of wholesale. The Dust Devil Mine is a bit hard to get to, but they have files for downloading to GPS units on their web-site. About 100 miles to the southeast is another Sunstone location, with the major mining carried out is at the Ponderosa Mine in Harney County. The Ponderosa is a relatively recent find, having been discovered in 1980.
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In general, Feldspar, also called Labradorite, is a little known and underrated gemstone, yet some of the available colors and varieties of material are truly beautiful. At a hardness of 6, it is generally too soft for daily use in rings, it would be acceptable for occasional wear for special occasions and other types of jewelry. Feldspar is an easy material to cut, both in cabs and for faceting. The two perfect cleavages are not troublesome, and in fact, the table for faceted stones does not always have to be oriented away from the cleavage planes. The material is not heat sensitive and polishing usually goes fairly quickly with Cerium Oxide.
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Thanks to the owners of the Dust Devil MIne for their pictures and sample sunstone specimuns.
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