For a few months now, I’ve been tempted by the idea of bringing in contributors to legemmologue.com. You could, for example, read Marine Chabin ‘s excellent article on jewellery know-how. Claire Fillet with the podcast “Rubis sur Canapé” joined the adventure. Today, Emmanuel Thoreux – now a trader in American gems with his company White River Gems – offers you a first paper on the famous sunstones that have made Oregon famous. Enjoy your reading!
22.89 carat red Oregon Sunstone, PANA Mine, cut by Jeff Hapeman. Photo: Ales Patrick Krivanek
By Emmanuel Thoreux (DUG Nantes, ING)
According to a Native American legend, a great battle took place near the Ochocos Mountains in Oregon: a valiant warrior was pierced by an arrow and his blood flowed onto pieces of sunstone. The blood inhabited by the spirit of this great warrior would then impregnate these stones to colour them a powerful and sacred red..
Today, a few courageous people, lost in the depths of the desert of south-eastern Oregon, are keeping the legend alive by investing body and soul in extracting and making us know this fabulous gem, theOregon Sunstone.
Heavily chastened since the beginning of the 21st century by the scandal of feldspars treated by copper diffusion and by the subprime crisis of 2008, Oregon sunstone, like the phoenix, is in the process of being reborn from its ashes: legal (to protect itself), associative (to organize itself) and marketing (to promote) initiatives initiated several years ago have brought this magnificent gem back to the forefront of the international market, resulting in a constant rise in prices for several months now.
This article aims to make you discover the beauty of this gem and the men who exploit it.
2-Oregon Sunstone is a feldspar, but not just any feldspar!
Oregon Sunstone is a feldspar with a wide variety of colours. Photo: A.P. Krivanek
Oregon sunstone is a member of the feldspar family. Feldspars are the most abundant minerals in the earth’s crust and are found, for example, in the composition of granite with quartz and mica, but also in gem quality.
Feldspars are more or less homogeneous aluminium tectosilicates composed of three elementary constituents (Carron, 2001):
- a sodium feldspar (Albite)
- a calcium feldspar (Anorthite)
- a potassium feldspar (Orthose, sanidine or microcline)
In nature, most feldspars are clearly divided into two categories:
- Calc-sodium feldspars or plagioclases (very low in potassium)
- Alkali feldspars (very low in calcium)
Among the calcosodic feldspars or plagioclases, we find minerals that are very important in gemology such as andesine, labradorite and oligoclase, which can often be found in the trade as moonstone or sunstone.
Oregon sunstone is a natural cupriferous feldspar of the labradorite type (An70/Ab30) and owes its very varied colours to the presence of copper in its crystal structure (Pay & Al., 2013).
3- Southeast Oregon, a vast playground
Oregon Sunstones researchers at PANA Mine. Photo: A.P. Krivanek
Oregon Sunstone is found in two distinct areas in southeastern Oregon: the first is a few miles north of Burns in the vicinity of theOchoco Forest with the Ponderosa Mine; the second is a good 100 miles south in the vicinity of Rabbit Basin and near the small town of Plush with the Dust Devil and Sunstone Butte mines in particular.
Map showing the main Oregon Sunstones mines, illustration by Larry Lavitt.
4-Geology for Sunstones
Oregon Sunstones are found in a volcanic environment. A major volcanic episode that occurred between 15 and 17 million years ago uncovered the Sunstones that are found today as phenocrysts in ancient, highly porphyritic lava flows. It is assumed that the gems were formed in magma chambers caused by magmatism generated by the meeting of two tectonic plates and then expelled by volcanoes and/or stratovolcanoes (Pay & Al., 2013).
Oregon Sunstones among unsorted volcanic rock. Photo: A.P. Krivanek.
5- The phoenix awakens!
To survive the turbulence of the early 2000s, the men ofOregon Sunstone had to take many initiatives to bring this magnificent gem with its incredible colours and effects back to life.
First of all, to protect the name ” Oregon Sunstone “: There is a great desire on the part of the operators to makeOregon Sunstone synonymous with a totally natural stone, i.e. without any treatment and in this way to differentiate it from the gem feldspars treated by diffusion. As of August 4, 2015, ” Oregon Sunstone ” is a trademark registered by Nirinjan Khalsa under the authority of the US government (No. 4784808) and designates a natural feldspar of the labradorite type found in southeast Oregon, USA. The use of the nameOregon Sunstone in a misleading manner can therefore legitimately lead to legal action, particularly on American territory.
Secondly, to get organised: following the various scandals involving feldspars treated by diffusion and sometimes sold throughout the world as Oregon Sunstone, the miners and main players in this gem have decided to form an association. Permanent members include: Dust Devil Mining, Sunstone Butte Mine, Ponderosa Mine, Work Um Hard #4, Suncrystal Mining, Sunrise Sunstones, Horizon Gems. TheOregon Sunstone Miners Association (OSMA) is dedicated to maintaining the integrity of the image and market of Oregon Sunstone as a rare, all-natural, all-American gem. If you buy from an OSMA member, you can be sure that the gem, whether rough or cut, is untreated and unenhanced, and comes from Harney or Lake counties in Oregon, USA.
Not forgetting to promote: promotion is an essential factor in rediscovering this magnificent gem. So a great idea came from two long-time friends: Ales Patrick Krivaneck, owner of the PANA concession and mine, and Eric Bardawil, a great connoisseur and lover of Oregon Sunstones. The result of this idea is a website, now translated into German and French. This guide brings together everything you need to know about this gem: its history, its actors, its characteristics. But it is also a participative site, any person working with the gem, be it a gemologist, jeweller or dealer, is invited to testify on the Oregon Sunstone through his own work. With a wealth of photographs and testimonials, the site is a reference for the promotion of this gem in the world.
To go further, it is necessary to understand and share by relying on rigorous scientific articles. This is one of the functions of the gemologist. One of the surprising characteristics ofOregon Sunstone is the possible presence of both red and green colours in the same stone, notably in a distribution known as “watermelon”, a term already used for tourmaline. A recent article reports the discovery of a mineral present in this type of gem labradorite from Oregon: protoenstatite, an inosilicate crystallising in the orthorhombic system. This article, currently being reviewed by The American Mineralogist, can be found here. Iron and aluminium-bearing protoenstatite was recently discovered in the Oregon Sunstones with an unusual red to green pleochroism. The presence of crystallographically oriented protoenstatite and clinoenstatite nano-crystals together with native copper nano-crystals is thought to be responsible for the green colour and “watermelon” coloration of this gem labradorite (Xu & Al., …).
Some specimens of rough bicoloured or “watermelon” Oregon Sunstone. Photo: A.P. Krivanek.
When cut by experienced lapidaries, these stones have absolutely beautiful and unique colour effects as shown in the photos below taken by the Krivanek family of PANA Mine:
Finally, let’s not forget thatOregon Sunstone is one of the most representative stones of the Schiller effect due to the presence of micro-inclusions of native copper, these inclusions are sometimes visible to the naked eye as demonstrated in the specimen below:
Oregon Sunstone of 5.13 carats with Schiller effect. Photo: Emmanuel Thoreux
As you may have gathered by now, I have fallen in love withOregon Sunstone and the people who work it. There is no such thing as a similar stone, they all have their own personality. Once cut, it still holds surprises, incredible and unexpected colour effects.
Oregon Sunstone is proudly rising up after years of gloom and I am happy to share with you the beauty of this stone that is still not well known here in Europe.
My warmest thanks to Ales Patrick Krivanek, his wife Katerina and his team at Pana Mine for allowing me to use their sublime photographs to illustrate this article.