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Information Circular Information Circular Pakistan.... Demuntoid Garnet- ll/ith enormous gem potentiul Rediscovered!! Pakistan - better known as a producer of some fine Demantoid, one most rare varieties of quality of emeralds up till few years back, but now of the Garnet group has been re-discovered in the Urals in the recent past the gem and mineral world trade in Russia and is now encountered in the market have witnessed some extremely fine quality of much frequenth/ than ever other gemstones from the region. Some of the before. minerals make the country / region prominent in Demantoid, the terrn is derived from the Dutch the mineral world. warddemant, meaning diamond. Demantoid was first discovered in the mid to late 1800s in Russia Pakistan is bounded by Afghanistan in the during the reign of Czar Alexander II. The newly nofthwest, while India in the east and Iran in the discovered gemstone $/est. The northern and northwestern part of made an impressive showing, enhancing the Russian Pakistan produces the maximum number of cultural life of nobles. gemstones. Three world famous ranges Demantoids were used by Karl Faberge' in combination with enamel gold his jewel Hindkush, Himalayas and Karakoram, enclose the and in creations for royal treasures. gem producing region. Demantoid belongs to lhe andradite a Sorne of the well- known gem species supplied to species calcium iron silicate; CarFe,(SiO.),. The stones the world market from the region includes aquamarine, topaz, Peridot, ruby, emerald, range in colour from pale green to yellowish green green. amethyst, morganite, Zoisite, spinel, sphene, to emerald The colour of Demantoid tou rma line, spessartite and demantoid. equivalent to fine emerald is very rare an emerald green is ideal for Demantoids. If the Pakistan has produced and still producing some same stone have a strong yellow as primary extremely fine quality of peridots, spessartite component and lesser green, it will be termed as garnets, orange topaz, chrome d'opsides and now 'Topazolite' the yellow coloured variety of recently demantoids. Andradite. The colour of Demantoid should be as intense as possible, without possessing black Looking at the mineral potential, the mining overtone or yellow secondary shade techniques and policies followed by the government is not up to the mark. I4ost of the Demantoid has derived its te!-m from diamond stones are mined by lhe locals / tribal people by because of its high brilliance and adamantine unconventional techniques thereby, lustre. The brilliance and lustre- both depends on compromising in quality and quantity. the refractive index. As the refractive index increases, the lustre and brilliance increases. Recently, at GTL, we analysed few samples of The RI Demantoid varies and Milky Chalcedony, Vesuvianite and a rarer gem of between 1,880 1.888- one species- Phenakite from Pakistan. Three samples of the highest values reported for natural coloured gem materials. of Phenakite were observed, which were colourless, refractive index varied between 1,652- Another feature of Demantoid is the high 1.671 with birefringence of around 0.018, clear dispersion of 0.057, while other garnets have low Uniaxial optic figure was resolved with positive to moderate of 0.022 to 0.028. The dispersion sign, specific gravlty measured at 2.95, all the value of Demantoid is even higher than that of three samples were eye clean but at higher diamond, which measures at 0.044. This high magnification, individual fingerprints were dispersion of both Demantoid and Diamond make observed with 2- phase inclusions. them an effective sim ula nt for each other. Canlnued ta page 3. Conhued to page 1. Continuecl from page 1. Some basic properties of Demantoid are as The original locality of Demantoid was in Ural follows: Mountains in Russia. It is found in alluvial deposits Sissersk Crystal System : Cubic; crystals vary from well of the District, Nizhni-Tagil and from formed to water worn pebbles. Crystals often are Bobrovka River. do-deca hed ron in shapes. The Bobrovka River in the Ural Mountain region Optic character : Isotropic (SR) has historically been considered as the premiere Refractive Index : 1.880 1.888 (SR) source of Demantoids. Currently, extremely fine Dispersion :0.057 Dementoid being brought out is limited, with Lustre : adamantine commercial material more easily available. Ural Hard ness : 6.5to7 Demantoids are qenerally smaller in size than Specific Gravity i 3.84 those found at other newer sources including Namibia, Italy, Iran, S pectru m : strong band at 443nm, and Pakistan. Compared to weaker bands at 622 and 640, dou blet at 693. the Russian Demantoids, Namibian stones have more blackish overtone that makes the stone less The colour of Demantoid is due to the presence of expensive. trace elements - iron and chromium. Iron is present in its ferric as well as ferrous states giving Demantoid can be confused with other member of variations in body colourfrom yellow to green. The the same group Tsavorite, which can be presence of chromium produces emerald green. differentiated by its lower lustre and dispersion, lower RI and different spectrum. Other materials, Recentl, we got a chance to analyze few which imitate Demantoid, are Glass, Yttrium Demantoids from Russia courtesy lV r. Mehul Aluminium Garnet (YAG), Natural Zircon, Durlabhji, Co-convener, GTL, who kindly donated Synthetic Cubic Zirconia, Diamond, the samples to us for study. The samples ranged in Green Tourmaline, etc. size from 0.10 carat to 0.43 carat, and the colour ranged from light green to dark green with the The most characteristic Feature for Demantoid is secondary yellow colour. The optical and physical its lustre and brilliance along with the inclusions propedies were consistent with those described and spectrum- Glass has got a lower lustre and Demantoid. for Almost all the samples had presence of gas bubbles, YAG can be characteristic'horse-tail' inclusion- the stamp of differentiated on the basis of higher SG of 4.60, Demantoids. and Natural Zircon is identified on the basis of These are basically, byssolite (fibrous form of strong doubling and characteristic spectrum at amphibole) and/ or chrysotile (fibrous form of 653.5n m. serpentine), forming a comet-like pattern. These Synthetic Cubic Zirconia can be differentiated by appear as fine strands connected at one end by a higher heft, having SG of 5.40 to 6.20 and high common centre; sometimes this centre could dispersion. creen Diamond is identified on the have a crystal of Chromite. basis of its lower SG of 3.52 and inclusions, while tourmaline by its lower SG, lustre, anisotropic natu re and strong pleoch roism. Demantoid's fire / brilliance is best seen in lighter, less saturated gems. Thus, the colour preference varies from individual to individual; some prefer an intense body colour and less fire, while others prefer a lighter body colour and more fire. It should be noted that that Demantoids look best under daylight. Incandescent light makes the stone more yellowish; also diffused lighting should be avoided while observing the brilliance of the sto ne. INFORIVIATION CIR 2 Continued lrom paqe 1.. Pakistan GTLians' corner... Dr. Treat (er) and his Summer N4 in ing a reas.... The few potential / major gemstone mining areas in Pakistan are: Holidays.,. with. ...Ru by 7" summer - Dr. Treater in India N Frontier Province orthwest Dr Treat: Ms. Ruby, how are you? What has happened . Swat (I4alakand division) : Emerald, Quartz and to you, so du ll, highly cracked I Epid ote Ruby: Yes, doc. it's my nature, I am born like thisl . Dir (lvlalakand division) : Corundum and Quartz Dr. Treat: Come, I will treat you. I will dye you so that those cracks will not be seen. l'4ansehra (Hazara division) : Corundum and Ruby: Tha nks doc. Quartz Next day, Ruby gets treated with coloured oil / dye and . Kohistan (Hazara division) : Peridot, Demantoid then unfortunately lives a life of tragedy with those . Peshawar district (Frontier province) : Quartz, 'colour patches along the cracks'. Xenotime and Bastnaesite 2"o summer Dr. Treat in Sri Lanka Dr. Treat: Ms. Ruby, Why you are so unevenly coloured, Federa lly Administered Tribdl Areas why there are colour patches in you? Have you been . Mohmand Agengy : Emerald, Clinozoisite, treated? Sphene and Epidote Ruby: No doc., I have not been treated! This is my . BajaurAgency : Emerald, Garnet,and Scapolite nature I am born like thisl Dr. Treat: C'mon I will treat you and remove all those . Khyber Agency : Quartz, Xenotime and patches by givin9 you a high temperature heatl Bastnaesite Ruby: No thanks doc. I don't want to be treated; I am . North and South Waziristan Agencies : Quartz okay as I am. But... Northern Areas Next day, she gets treated under high temperature . Chilas (Diamer district): Diopside, Zircon, and...she cries with pain- giving 'melted crystals' and Qua rtz, Aquamarine, and Tourmaline shouts at the doctor by creating 'bu rst halos'. Gilgi, Hunza and Shigar (Gilgit district): Beryl, 3'o summer Dr. Treat in Burma Topaz,Emerald, Quartz, Apatite, Spinel, and Dr. Treat: Ms. Ruby, you remember I treated your Sri Pa rg a site Lankan counterpart at high temperature, but I could not hide the large fractures! . Shengus, Stak Nala and Tormiq Nala (Baltistan Ruby: why you district): Beryl, Topaz, Tourmaline, Apatite, Yes, doc, but are saying this to me? What do you want from me? Sp hene, and Quartz Dr Treat: Oh! Nothing, I justwantto hide yourfractures . Chlldee, Kashmal and Yuno (Shigar area, with some glassy material and then you will appear Baltistan district) : Beryl, Tourmaline, Apatite, much better. To paz, and Quartz Ruby:Oh!Nodoc, I just want to be as I am. Hyderabad, Testun, Dassu, Net Tahirabad and But.... Goyunqo (Shigar area, Baltistan district): Topaz Next day, she gets filled with silica glass based (best quality), Beryl, Emerald, Apatite, and materials borax/ glass and carrying'alien substances' in her womb.
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