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Spectrolite Gemstones -Rare form of the labradorite feldspar

Introduction

Spectrolite is a very rare form of the labradorite feldspar and has a wider range of colors than the latter. Labradorite only exhibits shades of blue, gray and green. Spectrolite also has a much higher labradorescence than labradorite itself. Initially the name was only used as a trade name for the labradorite that came from Finland, but even today, it is still being used as a misnomer for any labradorite that is found having a different color from the three main ones mentioned above, even when it is found in areas outside Finland. For example, there is a labradorite variety which is found in Madagascar, that displays a play of color similar to that of spectrolite, but is still a labradorite, and yet it is called a spectrolite. The main difference between Spectrolite that comes from Finland and all other labradorite varieties is the fact that the Finnish variety has a strong coloring than all other labradorite varieties. The reason behind this is the fact that Spectrolite has a stronger black base than all other labradorite forms. The typical labradorite has a transparent black base color. The main cut used for Spectrolite is the cabochon, which is the same for any plain labradorite, in order to enhance the labradorescence of the gemstone.

The spectrolite gemstones from Finland

A Finnish geologist, Aarne Laitakari, who lived between the years of 1890 and 1975, first described this gemstone and for many years searched for the source, in the company of his son Pekka. They both found the deposit at Ylamaa, which is to the South East of Finland, as they were building Salpa Line fortifications in the year 1940. The gemstone from Finland exhibited a very unique and vivid iridescence and the full color spectrum, and this is the reason why it was called ‘spectrolite.’ It was Aarne who came up with the name. It was after this discovery and subsequent naming that the term spectrolite was wrongly used to describe some other forms of labradorite.

It was only after the Second World War that the quarrying of this mineral began in earnest, and it is now a significant industry and source of income for the locals. In the year 1973, the first workshop was started in Ylamaa for the cutting and polishing of spectrolite to be used in jewelry.

A deeper look at the physical and chemical properties of spectrolite

The first thing that is quite notable about spectrolite is the perfect display of colors caused by the fact that it has a deep black background to provide a higher level of contrast allowing the colors to be clearer. This is a feature that is called labradorescence since it is peculiar only to the group of stones called labradorite feldspars and spectrolite is one of them

What causes labradorescence?

Labradorescence does not refer to the way a gemstone can display many colors off the surface of the specimen. When light enters the gemstone, it will be reflected off the twinned layers that are in the structure of the crystal. The colors that the stone emits are due to the way that the light bounces off these tinned surfaces. Each of the many twinning surfaces within the stone will reflect light in a different color, and this is why the stone will have many colors. The light that bounces from different twinning surfaces from different parts of the stone are what give it the multi-colored characteristic that it is famed for.

Properties of spectrolite gemstone

Since spectrolite is a variety of labradorite, it will have properties similar to labradorite, apart from the fact that it will have a deeper black color. This is a gemstone that comes from the plagioclase minerals, namely the feldspars.  The cleavage of this gemstone is in two planes and is perfect in both, and these planes intersect at an angle that ranges between 86 and 94 degrees. As is common to all plagioclase minerals, this gemstones exhibits twinning and striations along the cleavage faces. It has a hardness value that ranges from 6 to 6.5 on the Mohs scale.

When it comes to labradorescence, spectrolite has the strongest in all the plagioclase minerals. There are other plagioclase minerals, of the labradorite family that do bot exhibit this property. It is very difficult to tell a labradorite gemstone from other plagioclase minerals if it does not exhibit labradorescence. Therefore, it is sometimes necessary to use other methods of analysis on order to tell whether you are looking at a spectrolite labradorite with no labradorescence or another plagioclase gemstone; the methods include x-rays, optical tests, specific gravity and chemical analysis.

Spectrolite is black in color, but you can find the colors of the spectrum being reflected from within the crystal. This is an intermediate member of the solid solution series of plagioclase. It is classed as a tektosilicate and has a triclinic crystal system. The deposits are found in a habit of huge cleavable masses, and also as euhedral grains which are irregular. It can rarely be found as prismatic to tabular crystals.

The twinning of spectrolite is said to be polysynthetic lamellar twinning and follows the albite-law of twining. The twinning can sometimes be seen by the naked eye and appear as striations in the crystal. It has a specific gravity ranging between 2.5 and 2.9 and an index of refraction ranging between 1.560 and 1.572. It has a weak birefringence of 0.010. It has a hardness value of 6 to 6.5 on the Mohs scale as mentioned earlier. It has a luster that ranges from vitreous to pearly and is mostly opaque. It has a perfect cleavage in two different planes. It has a conchoidal fracture and a white streak. The colors that appear in the labradorescence are blue, yellow, green, orange and red. It has a diaphaneity that can be said to be transparent to translucent.

A profile of spectrolite

At the best, spectrolite, which is a labradorite that was found in Finland resembles a mixture of Ammolite and Black Opal. These are some of the other gemstones in the world that have a wonderful play of colors, and the name spectrolite was given to the gemstone due to this display of colors. The similarity can be used as a talking point to explain why this feldspar is mainly mined by miners from Australia, who have been looking for a cheap replacement for the opal. The difference in the prices of these gemstones is quite small. According to one cutter called Jason Penn, and who is based in Tijeras New Mexico, a town just 25 miles to the east of Albuquerque, when the spectrolite is in its finest form, the prices go as high as 100 dollars per stone. In reality, there is a very tiny gap between the two gemstones, given that the prices for spectrolite are not as high as those of the black opal, it is a big mystery as to why spectrolite is not used very much in the market. The only thing going for it is the fact
that it is quite beautiful to look at.

The low price of spectrolite, which has been used by dealers as the main reason why they buy it, is a double-edged sword. The low prices affect the mining since it becomes very expensive to get the gemstone from the deposits found in the tundra environs of Finland. When you consider that the price of diesel in the Scandinavian region is now at about 10 dollars per gallon, then it is too expensive to keep the heavy machinery used in mining this low-priced gemstone running. The supplies of this gemstone may have been high about five years ago, but today they have gone down to almost nothing. According to Penn, there are only fee people who have backlog stocks of spectrolite, and these are those who started mining the gemstone a long time ago, as soon as it was discovered.

The early 1990s was the period in which the most significant amounts of spectrolite hit the market. Today, as Penn says, there is very little material available for cutting, and this he says, is due to the fact that he does not get as many calls from miners as he used to a few years ago. Spectrolite is a gemstone that is also very difficult to cut, and Penn says that the fact that he does not get too many calls for the gemstone is not very worrying to him. However, there is still a part of him that would like to work on designs that have this wonderful gemstone. Considering all the challenges that are facing the mining and cutting of spectrolite, then it is a shame that the gemstone attracts such a low price, especially when you consider how beautifully vivid its colors are.

There is need to avoid making errors

As mentioned before, there is a tendency for people in the gemstone trade to wrongly use the name spectrolite for gemstones which are actually brighter colored labradorite varieties. The cutting of spectrolite is also a very delicate matter and should always be compared to the cutting of labradorite. The colors of labradorite will be found running in layers that are parallel to the surface. The owner of www.faceters.com, Jeff Graham, who was a cutter and dealer based in Tucson before he met his untimely death a short while ago, said in an interview that one should imagine a ream of paper lying flat, in a manner that the sheets of paper lie atop one another. This means that labradorite should be cut in a table that is perpendicular to these layers. If a cutter were to tilt the table for more than a degree or two, then the resultant gemstone will not have the best color spread possible. The more you slant away from the perpendicular, the more you lose the color spread. Just like labradorite, the spectrolite, which just like pal and ammolite, depends on how well light bounces off the top of the gemstone, in order to display all its magical colors. In order to get this feature to be shown to its best, it is important that the entire top part of the gemstone to be perfectly level. The polishing of the gemstone also requires a lot of skill and patience. Penn says that when you are cutting spectrolite directly into the color planes, you are also cutting over a cleavage plane. This is why the gemstone is said to be particularly challenging when it comes to cutting it.

The African vs. Finnish spectrolite

It is a true fact that Finland seems to have stopped producing spectrolite completely, but Africa now has taken up the mantle and there is quite a good supply of the gemstone coming from Madagascar. However, the color of the African spectrolite variety is gray, as opposed to that of the spectrolite from Finland which is completely black. Penn says that the black base provides a good background for better color contrast, and this is the reason why the African spectrolite does not have the oomph that is shown by the Finnish ones.

When you consider the range of colors, the Finnish spectrolite has a wider range as compared to that of the African counterpart. The main colors shown by spectrolite are a bouncy medium tone of blue, and a light green that remind one of the color of leaves in spring. Most times, the gemstone looks like one of the pictures of the earth, taken by satellites from deep in space. There are times when you will see some yellow and orange hints in the color. There are also extremely rare times when you will see some blotches of red and purple, and these are the colors that collectors really search for, mostly in vain.

However, given that spectrolite has a low hardness value of only 6 on the Mohs scale and is susceptible to cleaving, then it is not good for setting into rings. Most spectrolite specimens are used for the making of earrings and pendants. When you consider that the gemstone will swing a lot when worn as an earring, or a necklace, this may be the very best use for the gemstone. The reason why, is the fact that spectrolite has to stimulated by the illumination from overhead light so that it can emit the best labradorescence. Furthermore, the necklace and earring would need to be in large sizes and this would bring out the colors more vividly, as opposed to the small stone sizes that are used for rings. The colors of spectrolite make it the perfect ambassador, from one of the countries where the northern lights and midnight suns are seen.

A few selling tips for the spectrolite

  • When one needs to have the same color display exhibited by the black opal, one can buy the spectrolite at a fraction of the price.
  • There is an increase in the rarity of the gemstone and this will make it very dear in the future.
  • There are no two spectrolite specimens that are alike and this makes it possible to have unique jewelry at a fraction of the normal cost, when using other similar gemstones – those that have unique colors and patterns.
  • It is easy to get spectrolite in large sizes.
  • This is a gemstone that will look fantastic as an accessory to all dark and gray clothing.
Spectrolite as a gemstone

Spectrolite is quite popular as a gemstone simply because of the iridescent exhibition of colors which is known as labradorescence. The quality. Tints and brilliance of colors will vary from one gemstone to the next. The stones are usually very bright in color, when you compare them to other labradorite gemstones and this is the reason they were accorded the name, spectrolite. It is very rare to find spectrolite in a jewelry store that deals in mass market jewelry, but it is most sought by designers and jewelers who specialize in making unique pieces that will be available to a few collectors and connoisseurs.

Spectrolite is able to produce fantastic jewelry due to this unique color display, and there are some that exhibit another optical character known as aventurescence.

A lot of caution should be exercised when cutting and polishing spectrolite into a gemstone for jewelry. The perfect cleavage in two different directions makes it very brittle. This means that the gemstone will simply split apart if it gets a hard knock and that is why it is rarely set into rings. The softness of the gemstone also makes it very susceptible to scratches and other abrasions.

Generally, spectrolite is a special gemstone, which needs to be marketed a lot more so the general public can get to know about it. It is unfortunate that there is little supply of the Finnish variety which is a lot more brilliant than that which comes from Africa. When all is said and done, this is a gemstone that can be worn with a wide range of clothes but mostly those which are black or gray, since they set of the labradorescence better.



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