OLIGOCLASE North Carolina Faceted Gemstone Fancy Triangle 9.19cts USA08

Sold by GEMSOFAMERICA
$895.00
+ $15.00 shipping

Only 1 available

$895.00
+ $15.00 shipping
In stock
Preparation takes 1-3 business days
Arrives from the United States
Returns and exchanges accepted
See this seller's return policy

Features
Vintage

Item details

Oligoclase feldspar faceted gemstone, an extremely rare colorless fancy triangle from North Carolina, weighing 9.19 carats and with dimensions 15.0 x 10.0mm

Gem feldspars, once considered just curiosities for collectors, have become mainstream jewelry stones. Best know among them is arguably the labradorite in myriad colors (sunstone) that is found in several areas of Oregon, as well as the magnificent blue and peacock-colored labradorite from the Malagasay Republic and Finland (spectrolite) and the super-brilliant faceted labradorite from Mexico trademarked as golden sunstone. Also common in the marketplace are moonstones from India, Sri Lanka and elsewhere, and an orangy spangled material, also called sunstone, that has been extracted from India for decades. Little by little, other feldspr gems are becoming more popular as awareness of them increases.

The feldspars, a large group of mineral species, are the most abundant minerals in the earth's crust. It was once estimated that if the entire crust of the planet could be ground up, mixed and analyzed, the resulting chemical formula would closely resemble that of a typical feldspar. But the group is extremely complex and, even today, the details of feldspar structure and formation are not well understood. Broadly there are two groups, all of them structurally made up of aluminosilicate frameworks: alkali feldspars (minerals based on potassium) and plagioclase feldspars (based on calcium and sodium). All of them are occasionally found in crystals that are transparent and can be faceted as gems. Some are only found in very small sizes, and some can be very large indeed.

The potassium feldspars include microcline, orthoclase, sanidine and anorthoclase. The gigantic yellow transparent feldspar crystals from Madagascar can yield stones over 1,000 carats. This material for decades was called orthoclase, but more recently has been properly identified as sanidine. Microcline occurs in many colors, and the blue-green variety has long been cut as cabochons and marketed as amazonite. The plagioiclase family is a group scientifically categorized as a 'solid-solution series', with formulas that have pure sodium at one end and pure calcium at the other. Mineralogists now label plagioclases according to the ratio of sodium versus potassium, but for a century the series was arbitrarily divided by chemistry into 6 equal partitions, each labeled as a different mineral species. Starting at the sodium end, these are albite, oligoclase, andesine, labradorite, bytownite and anorthite. Except for feldspars that are chemically in the middle of this series (primarily labradorite), all the plagioclase gems are small, colorless and nondescript.

An exception is the oligoclase found more than a century ago near Bakersville, North Carolina. Large whitish crystals were discovered in a mica mine, the centers of which were transparent and cuttable. Most of this material is colorless but pale blue-green stones are also known from this and a few other small localities in North Carolina. Cut gems over 5 carats are extremely rare.

This faceted oligoclase is a museum piece at 9+ carats and flawless to the eye. Most people are unaware of the amazing brightness of certain cut feldspar gemstones, including oligoclase and golden sunstone. This magnificent and rare stone has been cut as a fancy triangle (difficult to photograph!) with a small triangular table and a high crown and deep pavilion. The polish is excellent and overall this is a brilliant, stunning (and wearable) collector gemstone.


FAQs

I sell vintage products that in most cases cannot be replaced. The quality and uniqueness of my items does not allow for negotiation on prices. While I may offer special promotional sales from time to time (such as free shipping on orders at my discretion ), my inventory prices are final as listed.

I have more than 60 years of experience in the world of gems and minerals. I am widely regarded as one of the leading authorities in the world on colored gemstones. After obtaining my Ph.D. in Mineralogy from Harvard University, I was a Smithsonian curator and went on to publish numerous books that are still among the most widely used references and guidebooks on crystals, gems and minerals in the world. The Color Encyclopedia of Gemstones has for 40 years been the world's most authoritative source of information on (and color pictures of) gemstones, including many of the rarest collector gems. You can feel 100% confident purchasing from my shop! Visit my own website for more information about my credentials http://www.joelarem.com

TO RETURN ITEMS: Joel E. Arem P.O. Box 5056 Laytonsville, Md. 20882 Once I receive your returned item, I will issue you a credit to your PayPal account MINUS YOUR SHIPPING COSTS to return them TO SEND A MONEY ORDER: Please make it out to: Joel E. Arem and mail it to me at P.O. Box 5056 Laytonsville, Maryland 20882. I will notify you as soon as it arrives and your order will be shipped.

I am more than happy to mail your purchase directly to the gift recipient! Just add their shipping address in NOTES TO SELLER when you check out, and let me know that it is a gift. And of course I will NOT include a sales receipt in their package. I am happy to include a gift enclosure with your message on it. Just let me know what you'd like me to write for you.

I sell vintage products that in most cases cannot be replaced. The quality and uniqueness of my items does not allow for negotiation on prices. While I may offer special promotional sales from time to time (such as free shipping on orders at my discretion ), my inventory prices are final as listed.

I have more than 60 years of experience in the world of gems and minerals. I am widely regarded as one of the leading authorities in the world on colored gemstones. After obtaining my Ph.D. in Mineralogy from Harvard University, I was a Smithsonian curator and went on to publish numerous books that are still among the most widely used references and guidebooks on crystals, gems and minerals in the world. The Color Encyclopedia of Gemstones has for 40 years been the world's most authoritative source of information on (and color pictures of) gemstones, including many of the rarest collector gems. You can feel 100% confident purchasing from my shop! Visit my own website for more information about my credentials http://www.joelarem.com

TO RETURN ITEMS: Joel E. Arem P.O. Box 5056 Laytonsville, Md. 20882 Once I receive your returned item, I will issue you a credit to your PayPal account MINUS YOUR SHIPPING COSTS to return them TO SEND A MONEY ORDER: Please make it out to: Joel E. Arem and mail it to me at P.O. Box 5056 Laytonsville, Maryland 20882. I will notify you as soon as it arrives and your order will be shipped.

I am more than happy to mail your purchase directly to the gift recipient! Just add their shipping address in NOTES TO SELLER when you check out, and let me know that it is a gift. And of course I will NOT include a sales receipt in their package. I am happy to include a gift enclosure with your message on it. Just let me know what you'd like me to write for you.



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