Clinohumite – the Mountain Fire

Эксперт-геммолог

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In the region of the Tadjik Pamir mountain range, which locals call «the roof of the world» clinohumite has well known long before its official discovery.

The Pamir mountain people have always thought that the sun has protected them and helped them survive in the rough mountain conditions. It has helped them grow crops, hunt, and has always lighted the way in the difficult moments of life. One Pamir legend talks about the mountain people who, when attacked by the ruthless nomads, always hid from the assault in the gorge.

One time, however, the bloodthirsty criminals ambushed the people without warning. The mountain people barely had time to gather their elderly, woman, and children and send them to the safety of the gorge while their warriors held back the nomads to ensure their escape. The darkness of the night descended quickly on the mountains. The sun wished help the mountain people and tried stay in the sky as long as it could to light the way to safety. But the unforgiving mountains prevented the sun^,s efforts by bringing the darkness upon the helpless people. So, the sun decided to move mountains apart to help the people escape. It stone from the peaks of the angry mountains, fighting, and defying them by starting out and lighting the way. The people then made it to the gorge safely. Yet the sun, tired from its efforts, lost the unfair fight with the mountains and hit itself on the jagged peaks as it set. Afterwards, people would find pieces of yellow stone and were absolutely convinced that these were parts of the sun that broke off when it hit the mountains.

Image 1. Unique clinohumite of high gem quality, measuring 4x3,5x2,5 cm.i.

            Since then, finding a piece of the sun in the Pamir Mountains has been considered to bring incredible luck, so the mountain people would keep the pieces they found for centuries. They gave them as presents on their children^,s  wedding day, put them in their babies^, cradles, and placed them into the graves of their loved ones. Up to now, the natives still call this Pamir mountains gemstone «the mountain fire».

            A Clinohumite piece weighing in at 44 grams, which is described here, was given to a geologist as a gift by an old man who lived all life in a mountain settlement by the Ranj River on the Tajik-Afgan border. Hi told the geologist that he did not want to take this piece of the sun to his grave, knowing that his children wound certainly put the stone in there after he dies. «I want this stone to continue to shine its light on people», said the wise oil man. The elderly gentleman claimed to be 114 years old, and said that this particular stone had been in his family for over 400 yers.

Discovery and Gemology

            Clinohumite (Mg, Fe)₉(SiO₄)₄(F, OH)₂ is a member of the humite group, which also includes norbergite and chondrodit. It is practically impossible to tell the last two apart and their correct identification is only possible in a laboratory setting. Only chondrodite and clinohumite are used in jewelry and the latter is considered to be one of the rarest gemstones.

            Clinohumite was first discovered in 1876 in the Mount Vesuvius volcano in Monte Soma (Italy) by the French mineralogist and crystallographer and crystallographer, Alfred Des Clozeaux. That year the mineral was officially named clinohumite. Klino, derived from the Greek word meaning «to bend» is used to describe the particularity of its crystal cell structure. Humite it is group association. A detailed mineralogical description of the gem was composed by mineralogist, Edvard S. Dana, in 1892. Since then, this mineral did not incite much interest because it did not have any commercial aspects and no high quality samples had been found.

Image 2. Large cracks and muddy sports, which could have worsened spots, which could have worsened the cut stone^,s exterior appearance.

            Everything changed in1983 with the discovery of high gemstone quality clinohumite along with crystals of high quality spinel in deposit in Kukhilal, located in Southwest Pamir, Tajikistan, on the bank of the Ranj River. At that time, this was the only place where clear crystal of clinohumite, yielding 1 to 2-carat cut stones, were found.

            Today there are only a few known locations of gem quality clinohumite deposits in the word: (1) Taimir Penensula, Russia, in the northernmost point of the Euro-Asia continent, between the Yenisei River and the Lena River, with mining started in 2000; (2) Mahenge, Tanzania, in the Morogoro region where mining started in 2005. Both locations produce 2 to 3-carat stones when facetted.

Pamir Gemstone Quality Clinohumite

            In Pamir, the main deposit of gem quality clinohumite is Kukhilal, where the minerals is found in close association with high quality spinel. It is sometimes also found forsterite scarns where it is unevenly distributed.

            There two types of clinohumite mineralization: impregnated and blocked. The first type is widely found but is a poor source of high quality raw material. The second type is in a giant crystal formation, which is found in a scarn mass. This type of mineralization is the source of high quality clear clinohumite.

            Clinohumite does not usually possess crystallographic features. It is rare to find isometric clinohumite crystals which a large quality of grains. Most known crystal formation grow from a few millimeters to several centimeters, but some formations have reached 8 to 10 centimeters. Clinohumite grains mostly contain a high number of crack; therefore only small percentage of the raw material can be used for faceting this wonderful mineral. It is found in different colors: honey yellow, light yellow, orange, and yellow brown. A quality facetted clinohumite has a high value not only because of its beauty but also because of its rarity.

Image 3. The selection of a pear-shaped cut was mainly determined by the location of a lage open crack.

Gemological Particularities

It is very rare to find a high quality clinohumite facetted gem, which is very expensive and extremely prized by collectors. Geological publication generally mention only small cut stones up 3 carats. One of the largest clinohumite stones was documented in April 2007 by a team of geologist in a laboratory of the Asian institute of Gemological Sciences in Bangkok, Thailand. This faceted clinohumite orange in color and weighed 36,56 carats. Until then this was the largest known clinohumite in the world.

A Unique Sample

 

Image 4. A large loss of weight was due not only to a large number of defects but also to the form of the raw material.

            In summer 2010, a private collector from Moscow brought me a small batch of high quality clinohumite gems for diagnosis and cutting. Out of the batch, one stone was very unique, a very large clear gem suitable for cutting. The raw material, weighing 44 grams, was a broken bright yellowish brown crystal measuring 4х3,5х2,5 cm (Image 1).

            One look at this stone suggested that it would be extremely large after cutting. It was thus necessary to choose the optimal type of cut and down the cracks, mineral inclusions, and all other defects that would worsen the exterior appearance of this future gem. In images 2 to 4, a couple of large cracks and big muddy sports can be seen, which would reflect negatively on the cut stones exterior appearance. This is why selecting the right type of cut was extremely important.

 Image 5. Unique cut pear-shape oval clinohumite weighing 84,23 carats, measuring 25х24,4х18 mm.

            The most important part of this equation was to balance the optimal type of the cut while keeping the largest size possible. A large cut stone with an enormous number of muddy spots and open cracks would not have been interesting to anyone. At the same time, cutting several «small» clinohumites out of a unique stone such as this would have been foolish.

            The optimal cuts for the future gemstone were a tear, trapezoid, and a fantasy-inspired peak-like shape. The tear is one of the most beautiful forms of cut, but in this case, it turned out to be impractical for two reasons. First, the fragile stone could have broken during the rough-cut step. Secondly, a tear shape would have had minimal success. The cut form of an elongated trapezoid with a thick base and a thin upper part would not have been that appealing, although the usable material with this shape would have been much greater than with the pear-shape. In the end, the optimal form for the clinohumite was determined to be the peak-like oval.

            In history, there is a very well known green «Dresden» diamond, which is also cut in peak-like oval form, weighing 40,7 carats. Due in part to its enormous historic value and to its green apple color, it is virtually priceless. The decision to cut a pear-shaped clinohumite was based on the original form of the raw material and the locations of the cracks and inclusions. In image 3, the large open crack helped determined the ultimate cut of the stone.

Image 6. Unique cut pear-shape oval clinohumite weighing 84,23 carats, measuring 25х24,4х18 mm.

            Clinohumite is excellent as a cut material since it is very easy to work with and polish. Because of its rarity, it is very important to keep the dimensions and the mass as large as possible. Gemologist thus work on each piece of raw material individually. The gemstone is practically never used to make jewelry because of its rarity and fragility. Not every jeweler can skillfully set the stone. Very frequently, the most insignificant pressure on the gem during setting can lead to breakage. Consequently, most facetted clinohumites are found in private collections.

            A very high quality and unique clinohumite gemstone ended up in my possession. Working on such a stone would be an honor for any scientist-gemologist. An order to facet the stone was made and the skilled cutter tacked and finished the task quite brilliantly. He was able to cut the stone in just a couple of days, ending with an 84,23-carat piece. Today, this is the largest cut clinohumite in the world. The dimensions of this pear-like oval gem stone are 32,5х24,7 mm. Its height from the tip to the base is 18 mm. And the coloring of the stone is golden orange (Images 4 to 7).

            The authenticity of this fantastic stone has been confirmed by: Expert conclusion of the Moscow State University Gemological Center Research Laboratory (Registration Number D-22205 dated July 7, 2010); and an identification Report of the Gemological Institute of America (GIA Report 2125392151 dated 21, 2010).

            During the cutting process, the stone lost around 60 percent of its original weigh due mainly to the large and small cracks and defective muddy spots, which the cutter had file down during the process. The form of the raw material turned out to be very accessible and did not interfere with the plans for the stones form. During cutting, not only the character and the location of inclusion were factored in, but also the optical characteristics of the cut mineral. The technical order of the gemologist was executed in the skillful hands of the cutter to create an amazing one-of-a-kind facetted gemstone.

Image 7. Unique cut pear-shape oval clinohumite weighing 84,23 carats, measuring 25х24,4х18 mm.

            The uniqueness of this clinohumite includes its magnificent clarity. Its small inclusions only further confirm its natural creation and do not in any way affect the exterior appearance of the cut gem. One cannot forget that the stone is quite fragile, a fact proven during the stones examination when a gemologist at the Gemological Institute of America accidentally broke off its tip.

            The author hopes that that this particular specimen of Pamir clinohumite will take its place in the history book as a unique sample and will proudly join the world family of other record-holding stones. Taking into account the rarity of this mineral, it is very unlikely that a clinohumite larger than 84,23 carats will be found any time soon.