Sphene Gemstones - Titanite Gemstones
Introduction
There is a dichroic gemstone that has a very high dispersion, also known as brilliance, and has a beautiful yellow-green to green color. Similar to the diamond in terms of dispersion, the light that goes into the stone is broken down into the colors of the spectrum, and produces a brilliance that has all colors of the rainbow. This is a gemstone that has fantastic optical properties, far more superior than other gemstones, and is said to be more brilliant than a diamond. Sphene is said to be one of the most fantastic jewels in the world, and the only reason that it does not dominate the market, is because it is very soft, and also very rare. The hardness of Sphene is about 5 to 5.5, and this is very low for purposes of making lasting jewelry. The stone has to be worn with extreme care, especially when fashioned into a ring. However, this is a gemstone that is valued as a collector´s stone, where it can be stored and displayed in protected casings. It is one that you will not easily find on sale at jewelry stores, and the only ones that are in circulation can be found at special auctions.
The Baja California region in Mexico is the source if some of the finest yellow and green Sphene gemstones in the world. There are also some other fine green specimens found in Brazil. The gemstones are small, even though they have very thin crystals. However, one can, on rare occasions, get Sphene gemstones measuring above 10 carats in weight. Surprisingly, this is one of the few gemstones, which are extremely beautiful, and rare, and yet are quite affordable. This is a gemstone that is not treated, and there are no known techniques that can be used to enhance the stone; once again, the soft nature of the stone is the reason. Sphene is also called Titanite in some gemological circles.
Brilliant but little-known
One gemstone collector, had a very surprising introduction to Sphene; the collector was in a mood for green gemstones, and had just bought Rhyolite, Jade and Peridot, when the dealer gave the buyer some green gemstones, which were very brilliant, and said buyer thought that they must be the color-changing gemstones, since they has a lot of fire. However, the dealer said that these stones were known as Sphene. Once the buyer had a good look at the stones, he knew that he could not leave without having them.
Despite the fire exhibited by the stone, it does not change color; however, it is said to have more fire and brilliance than a diamond, and these come with gold and red flashes of light. The gemstone, also known as Titanite, comes in other colors, ranging from bright green to yellow. The yellow can sometimes be so intense that it looks like gold. The gemstone also comes in gray, white and black colors, which are collected as mineral specimens.
Sphene gemstone vs. Titanite gemstone
Many people will ask whether the name Sphene or Titanite is the correct name; well, both of them are correct. When talking to other gemologists, the term Sphene is the most acceptable. When talking to a mineralogist, you should use the term Titanite. Both terms can be used interchangeably, when you are looking to buy some of your own.
The formation of Sphene gemstones
This is a gemstone that is formed in the most common method, which is metamorphosis. The gemstone is called Titanite because it has a lot of titanium in its chemical composition. Chemically, this stone can be termed to be Calcium Titanium Silicon Oxide, CaTiSiO5.
Sphene, is usually found in igneous rock, but it is also found in schist and limestone, which has also been through the metamorphic process. Sphene, is the Greek word, which means wedge, from which the name Sphene is derived. It literally comes from the fat that the Sphene crystals are usually very thin. The thin crystals are usually found in twinned clusters. There are several colors found, and this is due to the type of trace elements that are found in the crystals; sometimes you will find some iron in the structure and this makes the color different from that which has a lot more titanium.
Sphene is found mainly from Pakistan, Russia, Italy, Madagascar, Brazil, Canada, Australia, California, and New York. The odd thing is that this was mined as a secondary mineral. This is a gemstone that makes for astonishingly beautiful jewelry; it is only those crystals that have great clarity, which are used for making faceted gems, which allow the fire and color of the stones to shine through. This is a stone that is considered to be quite soft, and this makes it unsuitable for making rings; this is best for earrings and pendants, which do not get too much rough treatment when they are worn.
All in all, the said buyer is now a proud owner of two beautiful Sphene gemstones, with one which has been put into a protective ring; it flanks a quartz stone and the sparkle of the stone really puts a flare to the whole ensemble; the look on people´s faces when told that this is Sphene and not Peridot is priceless.
Some consumer information about Sphene
It is very hard to say exactly what color Sphene is, it is even harder to take a photograph of this wonderful and brilliant gemstone. You see, the stone takes any light that has been thrown at it, and then breaks it up into several spectral colors; this means that any flash of light, will produce a stone, that show several colors reflected on the surface. This also means that when you photograph the stone from different angles, you will get a stone with different colors once again. However, one can say that every stone has a basic green color; when you look at some photos taken of a single pendant from different angles, you will understand what the text says. You may see yellow and green colors, from one angle, and red and green flashes when viewed from another angle. So one can safely say that Sphene has a basic green color, which has the colors of the rainbow mixed in somewhere.
Sphene is a fairly young gemstone, and it does not have much in terms of myths and legends. This was an unusual gemstone, known only to a few circle in the gemstone world, until a few years ago, when sizeable amounts were found in Brazil and the Far East. Today, there is a higher availability of Sphene, and it is now fairly well-known in the world.
Sphene is a gemstone that you can wear every day, but this should be done with extreme caution. It is quite brittle and soft, and therefore should be worn as a pendant, necklace or earrings. In order to get a ring stone, you need to use a fairly large stone, which will not break very easily. You should not wear this gemstone if you are going to do some tough activities. It will not do well with rough treatment. When worn as earrings and pendants, they swing freely, bringing about a dazzling display of colors to the wearer´s face.
The Sphene is a fairly priced stone at the moment and goes for the same price as a tourmaline stone. However, many people still wish that they could own a Sphene stone, due to its brilliance.
The Sphene is not currently a birthstone, but given its quick rise in popularity, it will soon be named as one.
There are some things that you should know before you go shopping for Sphene. To get a genuine Sphene gemstone, you have to go to an experienced and trained jeweler, otherwise you may end up with a low-quality stone. The jeweler must also have a lot of knowledge about colored gemstones, given that he should be dealing in them a lot. He may also have access to suppliers of colored gemstones. You should also be patient when looking for a good Sphene stone, since the gemstone is quite rare. You are looking for a gemstone that has a lot of fire, or dispersion. The quality of a nice Sphene stone, is one that has various colors coming out of it, since this is the hallmark that makes it to be very popular.
The Chemistry of Sphene gemstones
As mentioned earlier, Sphene can be termed as Calcium titanium silicon oxide, or otherwise known as Titanite. It is a fairly soft stone, with a hardness value of 5 to 5.5 on the Mohs scale, making it unsuitable for making rings. It has a prismatic cleavage which is distinct at 100; there may also be some parting of the crystal at 100. It has a density of 3.4 to 3.55 and has a monoclinic crystal structure.
The crystals of Sphene vary a lot in habit. They usually have a prominent basal plane, from which the sides, which are steeply inclined, rise. The sides are a combination of a pyramid and short prism face, which forms a thin, wedge-shaped crystal. It is common to get penetration and contact twins in the crystals.
This is a gemstone that has a vitreous and resinous luster and it has a transparent, translucent or opaque clarity. It has a refractive index of 1.9, 1.079 and 2.034. Due to the wide composition of the crystals, the refractive index changes highly. There was a specimen that was brought from St. Gothard, which had yellow light indices of 1.874, 1.894 and 2.0093. This is a gemstone that is pleochroic when found in yellow, pink and almost colorless crystals.
The structure and mineral composition
As mentioned earlier, Sphene gem is mainly found among igneous rocks, which is mainly as a result of the cooling and crystallization of molten magma, it is also found in schist and limestone which has undergone metamorphosis. In some cases, the most recent findings, it is said to be metasomatic in origin. Sphene is made up of approximately 40.8 percent of titanium oxide 30.6 percent of silica and 28.6 percent of lime. There are also trace elements of iron in the crystals. Apart from being found in the form of crystals, Sphene is also found in granular form, lamellar forms and compact masses. There are some crystals that have Iron oxide and others aluminum oxide.
Identifying Sphene
Titanite is said to be fusible at 4, and has a slight intumescence to a dark mass that resembles glass. This is a crystal that is attacked by hydrochloric acid. When it is fused with sodium carbonate, the resultant crystals can be dissolved in hydrochloric acid, and when the resultant solution is boiled in the presence of tin, it gives off a violet color, due to the presence of titanium.
Some of the varieties exhibit a reaction that is associated with manganese, especially when in bead form, and all show colors that are associated with titanium. Most of these varieties do dissolve to a certain extent in hydrochloric acid and give the same violet colored solution, whenever they are boiled with tin; all of these varieties are fully dissolved when placed in sulfuric acid. This is a mineral that is differentiated from garnet and staurolite in the way that it crystalizes, and the fact that it is very soft. It is also much harder than spharelite. It is also distinguished from other stones of the same color by the reaction that it exhibits when treated with tin, to show the presence of titanium.
Origins, Occurrences and Localities of Sphene
As mentioned, Sphene is found as a minor mineral in many acidic intrusive and metamorphic rocks, which under certain circumstances, were formed during the cooling of molten magma. It is also a product of the decomposition of rutile and ilmenite. It is also a common accessory mineral, found in igneous rocks, and is found in small amounts in granite, syenites, diorites, phonolites, trachytes, and many more. In Gneiss, crystalline limestone, chlorite-schist and other metamorphic rocks, you can find Sphene in large sizes. This is a mineral that is commonly associated with chlorite rocks. It has trace minerals of pyroxene, amphibole, zircon scapolite, iron ores, feldspar, quartz, apatite, among many others.
When it comes to localities, Sphene is found in so many places that it is difficult to tie it down to certain places. However, there are certain places where fine specimens of the mineral can be found. In Piedmont, Ala and St. Marcel are proud sources of fine crystals; other places are Zillerthal in Tyrol; they can also be found at St. Gothard in Tavetsch. In Moravia, the stones can be found in Zoptau. In New York, it is found in limestone deposits. The stones can also be found in Lewis, New Jersey as part of limestone deposits. Mexico and Brazil boast of very fine crystals, which are mainly used for making jewelry.
Sphene is mined in Russia, in the Kola Peninsula, where it is used for extracting titanium.
Some of the stone sizes by locality
It is very rare that you will find Sphene stones in sizes that are larger than 5 to 10 carats. It is often that you find a fine specimen, of about 5 carats being said to be very valuable. Generally, the minerals that come from India yield about 10 carats of cut stone. The rough that comes from Madagascar will yield a cut stone of about 15 carats. The Brazilian yellow Sphene can hardly ever be found in sizes that are above 5 carats. Those that come from Sri Lanka are usually about 10 carats. It is possible to find stones that are above 20 carats in Burma. However, the largest stones ever recorded are those which come from Baja, in Mexico.
In collections, you will rarely find chrome Sphene that has a fine color, and most of those found are in sizes below 3 carats. The Smithsonian Institute has a stone weighing 9.3 carats. In Switzerland, you get golden Sphene of about 8.5 carats. The largest brown is found in New York weighing in at 5.6. In private collections, the largest green Sphene is at 63 carats; an intense green stone was found in India, and was cut using a square emerald cut, and was flawlessly clear and had a lot of brilliance and weighed in at 106 carats; this is the largest cut Sphene in the world. The Devonian group found in Calgary, Alberta Canada has a red Sphene weighing in at 4.95 carats. The National Museum of Canada has a magnificent fine green Sphene that weighs in at 50.75 carats.
There are several gemological features of Sphene which make is astonishing to look at and make it valuable to a collector, or careful jewelry aficionado. It has a very high dispersion, which is perhaps the highest of all gemstones, and has been said to be higher than that of a diamond. However, the color of the body, the degree of inclusions and how the stone is cut can affect how much fire the final cut stone will exhibit. The luster of the stone can also come close to, or equal, to that of a diamonds, when it is properly polished. This is a gemstone that has a high birefringence, which brings about the doubling of the facet images which ones sees, and this can also cause the stone to have an internal fuzzy nature which is normally seen in zircon and Peridot.
There is a rare variety of Sphene, known as the chrome Sphene, has a deep green color which is brought about by the presence of high amounts of chromium. It is not possible to treat or enhance Sphene, and one cannot get imitations or synthetics. It is a very risky gemstone to cut or put into jewelry since it is soft and brittle. It has to be set protectively, or worn carefully when it is set in jewelry. This is a stone that should be protected from knocks and shock and should be kept away from heat; it also should not be exposed to acids. This should not be put in ultrasonic baths and steam. Mainly Sphene is kept in collections where it is kept under controlled environments.
The value of Sphene is measured just like that of most gemstones; the clarity, color and size are the most important. Most people have a preference for light stones such as the green, yellow, or light orange colors; these are the one that bring out the brilliance of Sphene gemstones to its best. The most valuable, as mentioned above, is the chrome Sphene. This is a stone that does not have high clarity, and they are rarely clean even when viewed with the naked eye. Those which have strong body color and high dispersion are, without a doubt, the most valuable Sphene stones that you can get.
