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Tourmaline, sapphire, peridot
The presentation discusses gemstones including tourmaline, sapphire, and peridot, detailing their characteristics, localities, identification, and geological occurrences. Tourmaline, classified as a semi-precious stone, comes in various colors and is found in several regions of Pakistan, while sapphire is a precious stone typically blue and hard, exhibiting various colors and classifications. Peridot, a rare gem-quality olivine, is primarily olive-green and found in specific geological settings, emphasizing the rarity of high-quality gemstones in nature.
Tourmaline, sapphire, peridot
- 2. The University OfAzad Jammu & Kashmir, Muzaffarabad Institute Of Geology Topic: Study of Gemstones: Tourmaline, Sapphire, Peridot Presented By: Group 03 Roll No: 18-24 Presented To: Sir Shahab Pervez
- 3. Fig 1. V-shapedBicolor Tourmaline Crystals on Smokey Quartz Paprok, Nuristan, Afghanistan. I. Tourmaline
- 4. The Presentation willcover: Introduction Locality of Tourmaline in Pakistan & AJK Physical Properties Optical Properties Geological Occurrences of Tourmaline Uses of Tourmaline
- 5. Introduction: The nameTourmaline comes from the Sinhalese term “turmali” meaning “mixed colored rock. The stone was first discovered by Dutch trader off the west coast of Italy in the late 1600’s or early 1700’s. At that time, these green tourmaline were assumed to be Emerald. Tourmaline is the birthstone for October, along with Opal. Tourmaline comes in a staggering variety of colors. This stone has one of the widest color ranges of all gems.
- 6. Tourmaline isa crystal boron silicate mineral compounded with elements such as Aluminum, iron, magnesium, sodium, lithium or potassium. Tourmaline is classified as a semi-precious stone and the gems comes in a wide variety of colors. Tourmaline is not a single mineral, but a group of isomorphous minerals with an identical crystal lattice.
- 7. The typesof tourmalines include: 1. Rubellite: Tourmaline that is red, purplish red, brownish red, orange-red, or pink. 2. Paraiba: An intense greenish blue, only found in the state of Paraiba, Brazil. 3. Chrome: Intense green. 4. Watermelon: Pink in the center and green around the outside.
- 8. THE MAP SHOWINGTHE MAJOR GEMSTONE OCCURRENCES OF PAKISTAN FROM GEOLOGICAL SURVEY (2002)
- 9. Locality of Tourmalinein Pakistan & AJK: Azad Jammu & Kashmir: Muzaffarabad District: Donga Nur Neelum Valley Jandaranwala Pegmatite Nangimali Palway Balochistan Region: Chagai District: Saindak Cu Deposit
- 11. Gilgit Baltistan: AstoreDistrict: Bulochi Drot Valley Hunza District: Upper Hunza Valley KPK Region: Chitral District: Chitral Mansehra District: Kaghan Valley Naran
- 12. Fig 2. Tourmalinefrom Pakistan Fig 3. Tourmaline from Palway, Neelum Valley, MZD District, AJK
- 13. Physical Properties: CrystalStructure: Tourmaline is a six member ring or the cyclosilicates having hexagonal crystal system. Color: Tourmaline has a variety of colors but pink, red, green, blue & multicoloured are its most well-known gem colors. Iron rich tourmaline are black to bluish black to deep brown. Iithium rich tourmaline are almost any color like blue, green, red, yellow etc. Magnesium rich tourmaline varieties are brown to yellow.
- 14. Hardness: 7-7.5 Specific Gravity: 2.9-3.3 Luster: Vitreous Streak: White Fracture: Conchodial to uneven. Cleavage: Indistinct Diagnostic Property: Lack of visible cleavage, prismatic crystal with rounded triangular cross section that are striated.
- 15. Optical Properties: Color& Pleochroism: Essentialy any color is possible, may also be colorless, strongly pleochroic. Cleavage: Not visible in thin section, grains are commonly fractured. Form: Occur as Euhedral to Subhedral. Relief: Moderate to high positive relief. Extinction: Parallel Optical Character: Uniaxial
- 16. Geological Occurrences: Commonin many granitic igneous rocks and in some metamorphic rocks. Commonly associated with quartz and K-feldspar. Often associated with Lepidolite, Beryl, Apatite or Flourite. The variety of tourmaline most often as an accessory minerals in black Schorl.
- 17. Uses: Used asJewelry gemstones and is cut into all forms and style. The Piezoelectric nature of tourmaline make it useful as a component of high pressure gauges. Black tourmaline used in purification.
- 18. II. Sapphire Fig 4.Showing , a selection of both rough and cut Kashmir sapphires
- 19. The Presentation willcover: Introduction General characteristic Identification Optical Properties Varieties of Sapphire
- 20. Introduction Sapphire isa precious gemstone, a variety of minerals corundum, consisting of Aluminium Oxide, with trace amount of elements such as iron, titanium chromium, vanadium or magnesium. It is typically blue but natural “fancy” sapphire also occur in yellow, purple, orange & green color. Commonly natural sapphire are cut and polished into gemstone and worn in jewelry. Sapphire is the birthstone for September.
- 21. General Characteristics Category:Oxide Mineral Formula: Al2O3 Crystal System: Trigonal Crystal Class: Hexagonal Scalenohedral
- 22. Identification Color: Typicallyblue but varies. Cleavage: Poor Fracture: Conchoidal, Splintery Twinning: Both grown twin in various orientation. Mohs Scale Hardness: 9.0 Lustre: Vitreous Streak: Colorless Specific gravity: ～3.98-4.06
- 23. Optical Properties Birefringences:0.008 Pleochroism: Strong Melting Point: 2030-2050°C Fusibility: Infusible Solubility: Insoluble
- 24. Varieties Of Sapphire Natural Sapphire Blue Sapphire Pink Sapphire Star Sapphire Padparadscha
- 25. Natural Sapphire • Sapphireis one of the two gem-varieties of corundum, the other being ruby. Although blue is the best-known sapphire color, they occur in other colors, including gray and black, and they can be colorless. • Sapphire and rubies are often found in the same geographical settings, but they generally have different geological formations. • The cost of natural sapphires varies depending on their color, clarity, size, cut, and overall quality.Sapphires that are completely untreated are worth far more than those that have been treated. Geographical origin also has a major impact on price. For most gems of one carat or more, an independent report from a respected laboratory. Fig 5. An uncut, rough yellow sapphire found at the Spokane Sapphire Mine near Helena, Montana.
- 26. Blue Sapphire • Bluesapphire exists in various mixtures of its primary (blue) and secondary hues, various tonal levels (shades) and at various levels of saturation (vividness). • Blue sapphires are evaluated based upon the purity of their blue hue. Violet & green are the most common secondary hues found in blue sapphires. • The highest prices are paid for gems that are pure blue and of vivid saturation. Gems that are of lower saturation, or are too dark or too light in tone are of less value. However, color preferences are a personal taste. Fig 6. Showing the Teardrop-shaped blue sapphire.
- 27. Pink Sapphire • Pinksapphires occur in shades from light to dark pink and deepen in color as the quantity of chromium increases. • The deeper the pink color, the higher their monetary value. In the United States, a minimum color saturation must be met to be called a ruby, otherwise the stone is referred to as a pink sapphire. Fig 7. Natural Pink Sapphire, Batakundi-Basil Area (Pakistan)
- 28. Star Sapphire • Astar sapphire is a type of sapphire that exhibits a star- like phenomenon known as asterism; red dstones are known as "star rubies". • Star sapphires contain intersecting needle-like inclusions following the underlying crystal structure that causes the appearance of a six-rayed star shaped pattern when viewed with a single overhead light source. • The value of a star sapphire depends not only on the weight of the stone, but also the body color, visibility, and intensity of the asterism. The color of the stone has more impact on the value than the visibility of the star. Fig 8. Light color, an oval shaped star sapphire found in Sri Lanka
- 29. Padparadscha • The nameis derived from the Sanskrit "padma ranga" (padma = lotus; ranga = color), a color akin to the lotus flower. • Padparadscha is a delicate, light to medium toned, pink- orange to orange-pink hued corundum, originally found in Sri Lanka. • Padparadscha sapphires are rare; the rarest of all is the totally natural variety, with no sign of artificial treatment. • Among the fancy (non-blue) sapphires, natural padparadscha fetch the highest prices. Fig 9. Faceted padparadscha, found in Sri Lanka.
- 30. III. Peridot Fig 10.Sapat Gali, Naran, Kaghan Valley, Mansehra District, KPK Province, Pakistan
- 31. The Presentation willcover: Introduction Locality Identification Appearance Geological Occurrence
- 32. Introduction It belongsto Olivine family. It is the birthstone for the month of August & it is said to be put ghosts & demons to flight, dispel melancholy & foolishness. Peridot sometimes called chrysolite, is gem-quality olivine and a silicate mineral with the formula of Mg2SiO4 Peridot is one of only two gems observed to be formed not in the Earth’s crust, but in molten rock of the upper mantle. Gem- quality peridot is rare to find on Earth's surface due to its susceptibility to weathering during transportation from deep within the mantle to the surface.
- 33. Locality It isfound near the Kohistan-Kaghan watershed to the NE of Naran. It occurs along shear zones and in pockets in dunitic host rocks and are associated with clinochlore, magnetite and magnesite. It occurs in the immediate hanging wall of the Indus Suture and possibly it may be found in the hanging wall of Karakoram suture. It represents the basal cumulates of the Sapat Gali (Manshera District) mafic-ultramafic complex.
- 34. Identification Color: Yellow,to yellow-green, olive-green, to brownish, sometimes a lime-green, to emerald-ish hue. Fracture: Conchoidal Mohs Scale Hardness: 6.5-7 Luster: Vitreous Streak: Colorless Specific Gravity: 3.2-4.3 Birefringence: +0.036 Melting Point: Very High Pleochroism: Weak pale yellow-green to yellow, yellow to yellow orange.
- 35. Appearance Peridot is oneof the few gemstones that occur in only one color: an olive-green. The intensity and tint of the green, however, depends on the percentage of iron in the crystal structure, so the color of individual peridot gems can vary from yellow, to olive, to brownish-green. In rare cases, peridot may have a medium-dark toned, pure green with no secondary yellow hue or brown mask. Lighter colored gems are due to lower iron concentrations.
- 36. Geological Occurrence Olivine,of which peridot is a type, is a common mineral in mafic and ultramafic rocks, often found in lava and in peridotite xenoliths of the mantle, which lava carries to the surface; however, gem-quality peridot occurs in only a fraction of these settings. Peridots can also be found in meteorites. Peridots can be differentiated by size and composition. A peridot formed as a result of volcanic activity tends to contain higher concentrations of lithium, nickel and zinc than those found in meteorites.
- 37. Olivine isan abundant mineral, but gem-quality peridot is rather rare due to its chemical instability on Earth's surface. Olivine is usually found as small grains and tends to exist in a heavilyweathered state, unsuitable for decorative use. Large crystals of forsterite, the variety most often used to cut peridot gems, are rare; as a result olivine is considered to be precious.
- 38. Gallery Fig 11. Peridotolivine with minor pyroxene, on vesicular basalt Fig 12. Olive green peridot. Fig 13. Peridot with milky inclusions
- 39.