Ads

Type Here to Get Search Results !

Sapphire in Kishtwar

There is a chance discovery of Sapphire (Neelam) "pride of JandK" mines in Paddar Pargana in 1881 A.D., during the Dogra rule of Maharaja Ranbir Singh. The mines are located at a height of about 4,267 meters or 14,000 feet above sea level on mountain top above mountain top above Suncham village some 40 kilometers from Atholi. In 1881 A.D., there was hardly any habitation in the village. Suncham is 3385 meters or 1,100 feet above sea level. Maharaja appointed an officer to look after the affairs of these mines. Necessary measures were taken to protect the mines. A department of mining was established in 1909 A.D. which was later on named as J&K Minerals Ltd. The extraction work has been stopped for the last two decades. The decision about scientific extraction of the world-wide famous sapphire was taken in the year 2007 and at that time the Government had ordered for sending teams of experts to Paddar for deciding modalities for preparation of integrated mining plan followed by floating of global tenders. Subsequently, the global tenders were floated for inviting expression of interest (EOI) for scientific extraction of sapphire from Paddar mines. Around seven companies participated in the EOI and three of them were shortlisted by a committee constituted for the purpose. The Government has continued manual extraction of the Sapphire from Paddar mines and during the year 2008, around three to four kilograms of rough Sapphire was extracted thereby raising the total quantity of sapphire with the Department to around 14 kilograms. After a long gap of 20 years when the sapphire extracted from Paddar mines in Kishtwar was put up for auction in the state and for the first time in the winter capital, some prickly issues which the government has always preferred to avoid too cropped up. Though this time the auction of 34 lots of rough Sapphire corundum with varied weights fetched a handsome amount of Rs 1.31 Cr, a far greater amount earned in the last auction held in Srinagar in 1988, yet the connoisseurs of this precious stone were not very appreciative of the quality of 40 lots on sale. This was in spite of the fact that Paddar Sapphire is perceived to be the best in the entire world for its unmatched qualities of durability, variety and beauty.

Properties of Kishtwar Sapphire

Property
Description
Color range/
phenomena
• Near colorless to a deep blue (almost black), including a highly prized, rich "velvety" blue that is considered sapphire nirvana to connoisseurs
• Rarely pink to purple
• Six-rayed stars have been reported
Geologic 
formation
Sapphire occurs at the contact zone of a pegmatite intruded into a marble, in association with actinolite-tremolite. They are most abundant where the intrusions are quartz-free and surrounded by the actinolite-tremolite. The crystals are found in lenticular pockets of kaolinized plagioclase feldspar.
Crystal habitSpindle-shaped hexagonal bipyramids are most common, sometimes terminated by the basal pinacoid. Most crystals are coated with a tenacious white kaolin clay. Dark brown tourmaline crystals are often found adhering to the crystal surfaces. The color generally lies near the tips and exterior surfaces of crystals, similar to ottu sapphires from Sri Lanka. Two distinct crystal types are found:
• Euhedral crystals, with flat faces, where the color layer is intact
• Corroded crystals where the color layer has been partly or completely dissolved. The blue color of such crystals often appears as mottled blue spots.
RI & 
birefringence
n[epsilon] = 1.762; n[omega] = 1.770      Bire. = 0.008
(based on one specimen only)
SG4.03 (based on one specimen only)
SpectraWeak to moderate Fe spectrum. Cr-rich stones may display a weak Cr spectrum superimposed on this.
FluorescenceUV: Generally inert (LW & SW); but often with small fluorescent orange zones, occasionally yellow in surface openings (LW)
Other featuresMay be heat treated
Inclusion types
Description
Solids• Allanite, euhedral crystals (Hänni, 1990a)
• Feldspar (plagioclase in strongly corroded crystals (Hänni, 1990a)
• Pargasite (amphibole), needles & prisms (Gübelin, 1973)
• Tourmaline (dravite): prisms, green to brown color (Gübelin, 1973)
• Uraninite, black crystals often embedded in zircon. When alone, they may have stress fractures around them. Uraninite crystals are distinctive and important in separating Kashmir sapphires from other sources. (Hänni, 1990a)
• Zircon: corroded crystals, sometimes long needles (Phukan, 1966)
Cavities
(liquids/gases/
solids)
• Primary cavities and negative crystals
• Secondary negative crystals (healed fractures) are distinctive and may contain black crystals (uraninite in the cavities)
Growth zoning• Straight, angular growth zoning parallel to the faces along which it formed. In Kashmir stones this is often composed of alternating clear and turbid zones. Such turbidity is responsible for the "velvety" appearance of many Kashmir stones.
• Color zoning is often restricted to the areas just beneath crystal faces; such stones are termed "ottu" in Sri Lanka
Twin development• Growth twins of unknown orientation
• Polysynthetic glide twinning on the rhombohedron
Exsolved solids• Rutile in fine clouds of generally tiny crystals, parallel to the hexagonal prism (3 directions at 60/120°) in the basal plane. This rutile tends to be much finer than that found in Burmese and Sri Lankan sapphires. Often only tiny particles are seen; these may occur in tiny "snowflake" patterns.
• Clusters of dust-like inclusions (probably rutile) which may resemble snowflakes
• Twinning needles parallel to the rhombohedron edges
Table is based on the author's first-hand experience, along with published reports of Gübelin (1953, 1973), Gübelin & Koivula (1986), Hänni (1990a), Phukan (1966) and Schwieger (1990).

Geology of Sapphire: The mines which are situated in highly rugged terrain of Himalayan Range remains almost snow bound. Perpetual snow covered glistering vitreous mountains, rising as high as more than 5500 Mts. deep gorge's and precipitous defiles, cirques and amphitheaters, U-shaped glacial valley and hanging valleys all combine in the central Himalayan topography. The glacial carved out valleys represent a steep like longitudinal profile. Alluvial fans are seen throughout the paddar area. The weathering conditions smooth their way to gentler slopes and torrential stream gets away along it; a flat ground comes into existence. These flat grounds have been inhabited by the people from the villages like Garh and Masu. Besides, these river terraces are by no means uncommon in the paddar area. The town of Atholi and village of Kijai are situated on such terraces. There is the considerable moisture in the area because of the enormous heights. This area remains considerably under the clouds when monsoon attacks the plains. Average temperature during the working season of July to September remains around 5°C to 10°C during the day and almost minus 1-2°C during night. However, in the mine, the temperature is always minus 2-10°C.
The whole Paddar area has undergone Regional metamorphism as one moves from Kishtwar to the Sapphire mine area. The original Argillaceous rocks subjected to Metamorphism changed the chlorite under Epidote - Amphibolite Facies as under:
Mg3Si2O5 (OH)4+KAlSi3O5=KMgAISi3O10 (OH)2+2Si2O+H2O
(Antigorite)
(Orthoclase)
(Biotite)
(Quartz)
(Water)

Properties of Sapphire: Sapphire is a Greek word meaning Blue. Kishtwar Sapphire is known as King of Sapphires. The brilliance exhibited by it is of a rare quality and fetches the highest possible price per carat. Its deep blue colour with cornflower tinge is its specific colour characteristic. The velvety touch called as mercurial colour resembles to the neck of a peacock; which provides the only discernible characteristics of the stone from rest of the world. Inclusion of rutile needles result in silky sheen. Sapphire exists in the Rhombohedral form, the prominent face read 2243 /\ 2423 = 51° 58' between two prismatic faces. Crystal faces show striation and etch-mark. The majority of the crystals ranging from 0.8 inches to 1.5 inches in length are very much transparent, but, the crystals, which are beyond two inch in length, are mostly opaque and translucent. The hardness of the sapphire is nine as per the Moh's scale of hardness. The sapphire crystals are usually embedded in the fine matrix of kaolin transversing the pegmatite vein. The Kishtwar Sapphire under microscope shows that they are uniaxial in nature. They depict negative characters. A variety having satellite opalescence when viewed in the direction of vertical axis of the crystal is the asteriated Sapphire. Sapphire is strongly diachronic. Streak is white, Sp. Gr. 3.93 to 4, fracture uneven, Ref. Index 1.765, Double Ref. Index 0.08, Disperssion 0.018, Pleochroism is blue. Absorption spectrum Blues from 4710, with Flourscance.

Mining Activity in Paddar: J&K Minerals Limited has done mining activity in the area on a very small scale and the year wise details of Sapphire Corundum collected are as under:
YearProduction of Corundum Grams
1963-6450,000
1964-652,00,000
1965-662,24,000
1966-671,85,000
1967-681,83,672
1968-691,44,580
1969-701,40,415
1970-712,14,500
1971-72--
1972-73--
1973-7484,845
1974-75--
1975-76--
1976-77--
1998-992,696
1999-20001,807
2000-20013,460
2001-20021,340
2002-20031,297.5
2003-20043,294
2004-20053,215.50
The Gemstones are generally retrieved from screening of debris. This screened debris is subjected to splash of water which reflects upon wet gemstones getting picked up and are brought before Gemmologist for identification purpose. After visual identification by magnifiers, the corundum is segregated from sapphire. This segregated quality of sapphire is subjected to removal of Kaoline and other matrix. Concentrated Hydrochloric acid or Nitric acid is applied, as the case may be, in small proportions i.e. 100 gms. to 500 gms. And crystals are dipped in acid wash. After stirring for an hour the matrix gets dissolved and gemstone are retrieved. This is followed by passing the said stone through various sieves so that the size of the gemstone is established. Around 4 to 5 categories are made for evaluation and each and every piece in the sorted packet is properly weighed in carats for auction purpose.
Since we utilize 1 Kg to 2 Kg in a season of Hydrochloric Acid, as such, the waste of the said acid is properly disposed in a small pit, which is mostly covered on completion of job. Around 100CubicM of water is required for processing of debris which is stored in a pond near the mines and this water suffices for the entire period of operation of the expedition. There is thus no problem involved in disposing of waste water and extent of recycling.

Post a Comment

0 Comments