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Natural Treasures.

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Presentation on theme: "Natural Treasures."— Presentation transcript:

1 Natural Treasures

2 Precious Metals Naturally occurring Metallic elements Rare Valuable
Chemical attributes of a metal: solid, ductile, malleable, luster (shine), conducts electricity, also these are less reactive (more stable) than many elements

3 Precious Metals Graded on: Rarity Purity Mass
Purity often 99.9%, approaching but can never reach 100% Bullion = precious metal in bulk, value by weight, after refining but before processing into ingots (bars) or coins

4 Precious Metals Silver: current value $22.38 per ounce
Gold: current value $ per ounce 1 troy ounce = about 31 grams Price fluctuates according to supply and demand and other economic conditions Not going to say much about platinum, extremely rare, often found mixed in with other metals in alluvial deposits, mainly industrial applications, currently valued at $1399 / ounce

5 Silver Uses: coins, jewelry, mirrors, silverware
Found in ores with other elements Extracted through mining Major mining operations in Peru, China, and Mexico Other large mining operations are found in Australia, Bolivia, Russia, the US, Poland and Canada, also Argentina and Chile. In the United States, Nevada is the largest producer. Highest electrical conductivity, but more expensive than copper so not often used Though sometimes wires can be silver-plated Used in film photography, electronics, musical instruments Most often collected as a by-product of mining for other metals like copper, lead, zinc, or gold The largest silver nugget ever mined, weighing over a ton (900 kg), came from the Smuggler Mine in Colorado. At its peak the mine was responsible for nearly one-fifth of the world's total silver output Historically, silver has been mined in Peru, Mexico, and Bolivia since the 1500’s

6 Gold Uses: coins, jewelry, space research and other scientific advances, dentistry, electronics Native gold is often found as an alloy with silver. Extracted through mining, “panning for gold” in river sediments China and Australia are the biggest producers of gold. Other major gold mining operations take place in the US, Russia, and South Africa, also South America, Canada, and Indonesia. Gold can be found throughout the country. Mines in South Dakota and Nevada supply the majority of the gold in the United States. 24k (carat) gold is considered pure Alloys used to make it harder when used in circulated coins Before this, people would bite the coins to see if they were genuine gold Can take many different forms from flakes to ropey texture to nuggets

7 Gold Rush! Gold was first discovered in the US at the Reed Gold Mine in North Carolina in 1803. After that, gold rushes took place in Georgia, California, Colorado, and the Black Hills. Similar gold rushes took place in New Zealand, South Africa, and the Klondike region of Canada. Gold is found all over the world

8 Famous Finds Holtermann Nugget
found by Bernhardt Holtermann in Australia in 1872 weighed in at just under 640 lbs. This one was found in a hard rock mine, so not really a nugget per se

9 Famous Finds Welcome Stranger
found by John Deason and Richard Oates in Australia in 1869 weighing in at 2316 troy ounces (about 159 lbs.) Welcome Stranger was melted down, it may have been bigger but they had to break it down to weigh it They got over 2200 ounces out of it once it was refined

10 Famous Finds Hand of Faith found by Kevin Hiller in Australia in 1980
876 troy ounces (almost 62 lbs.) Using his metal detector outside his trailer in Victoria, Australia The story goes he got a signal, but thought his detector was acting up, so almost didn't dig! Sold it to the Golden Nugget Casino in Las Vegas for a million dollars, where it is now on display

11 Mining Sluicing Dredging Hard-rock mining
Some of the oldest known gold artifacts date between 4700 and 4200 BC, indicating that gold mining could be at least 7000 years old. Panning for gold not feasible on a large scale, only works when gold nuggets are large enough to be visible, mostly a tourist attraction today Rocker boxes used where water level is low, otherwise like sluicing Hard-rock mining may be in open air pits or up to 12,800 ft underground (requiring AC for people to work there) as in South Africa This is where most gold comes from today rather than placer mining (from river deposits) Can also be gathered as a by-product, as in Indonesia’s largest copper mine, which also produces a lot of gold

12 Processing Grind rocks containing gold.
Add sodium cyanide to dissolve it. Collect the new gold cyanide solution and add zinc to form a precipitate. Add sulfuric acid to remove the zinc. Collect the gold sludge and put it through a smelting process. Ship the gold to a metal refinery for final processing. Smelting is heating and extracting Environmental concerns with pollution Some processes use mercury With silver, it is often found with lead, and differences in solubility allow it to be dissolved in zinc which separates it from the lead, then zinc is evaporated and silver remains This is called the Parkes process and is more efficient and less hazardous than other methods, including those used in gold mining Electrolysis with copper can also be used to extract silver

13 Processing There, it is melted again and borax and soda ash are added, to remove unwanted impurities. Depending on its intended usage, the pure gold is then mixed with other metals to form an alloy. Gold ingots are formed. Pure gold is 24k 12k would be half gold, half some other metal The alloy is harder and more durable than pure gold, also adds color which we see in the jewelry trade

14 Precious Gems Pretty minerals used to make jewelry Graded based on
Color Cut Clarity Carats (size) Usually minerals, but some come from organic sources (like pearls) Intense colors are valued In diamonds, it is the cut and clarity that are most important, making it sparkle Clarity = purity, few to no inclusions Here, lab-created stones are the best Carat = 200 mg or 0.2 gram Value depends on the rarity of the gem as well as its quality Varies according to consumer market demands, or whatever is fashionable at the time Can be tens of thousands (or more) per carat Precious gems are more rare than naturally occurring metals They take a long time to form They are found in oldest parts of a continent Political situation also influences which areas are accessible

15 Precious Gems Precious gemstones Diamond Ruby Emerald Sapphire
The term comes from ancient Greece, and does not necessarily reflect which gems are the most rare and valuable

16 Diamond Formed from pure carbon Hardest known material
Used in jewelry as well as in cutting and polishing tools Formed under high temperature and pressure beneath the Earth’s surface, over a long period of time Derived from Greek “adamas” = unbreakable Its beauty comes from the structure of the crystal lattice 1,652 and 2,372 °F temp, 45K – 60K atmospheres of pressure, miles below the surface, in Earth’s mantle Time period is 1 billion to more than 3 billion years Typically, diamonds come from continental cratons (core of the continent, where crust is thick enough for diamond formation) volcano must reach deep enough to spew out the minerals Often, miners find indicator minerals to lead them to diamond mines Few are rich enough to be economically viable

17 Diamond Primary source: brought up by volcanic activity
Secondary source: dispersed by erosion It is thought that diamonds were first recognize in India, between 3,000 and 6,000 years ago in alluvial deposits

18 Diamond Mining 1725 was the first diamond discovery outside of India
Ore is crushed, then diamonds are sorted by density. The raw diamonds are traded or sold. Raw diamonds are then hand-picked, cut and refined. 1725 was the first diamond discovery outside of India Then the extraction from primary deposits started in the 1870’s and has increased since then They are mined from kimberlite and lamproite volcanic pipes

19 Diamond Mining Today, the most productive diamond mining operations are in Africa, Russia, Australia, and China. There are also productive diamond mines in India, Canada and Brazil. In the US, diamonds have been found in about a third of the states. Approximately 130,000,000 carats (26,000 kg) of diamonds are mined annually, with a total value of nearly $9 billion Roughly 49% of diamonds originate from Central and Southern Africa Found mostly in the interior parts of the US, where the continental craton is (the oldest part of the crust)

20 Mining is not so glamorous

21 Diamond Mining Blood diamonds
Kimberly Process established by UN in 2002 aimed to reduce sale of conflict diamonds, so the money can’t be used by rebel leaders to fund their wars and revolutions Canada has stricter rules and enforces conflict free diamonds Hard to trace stolen diamonds They can be marked but marks are just as easily removed

22 Diamond Color in diamonds comes from impurities. Synthetic diamonds
Nitrogen is the most common and creates the yellow and brown color of most diamonds. Synthetic diamonds Almost diamonds Synthetics use HPHT (high pressure, high temperature) process or CVD (chemical vapor deposition) Many for industrial uses, not as popular in jewelry, but colorful ones are often lab-grown Cubic zirconia or silicon carbide (less common) are synthetic simulants that look a lot like diamonds

23 It’s largest dimension is just over 4 inches in length
Famous Finds The Cullinan diamond is the largest gem-quality diamond ever found, at  carat (about 1.37 lb.) rough weight. It was found in South Africa in 1905. It’s largest dimension is just over 4 inches in length

24 Originally thought worthless for its color
Famous Finds The Golden Jubilee is the largest faceted diamond in the world. At  carats, it is larger than the Cullinan I, the largest diamond cut from the Cullinan raw stone, though it came from the same legendary mining grounds. Originally thought worthless for its color Henry Ho of Thailand bought it in 1995 and gave it to the king of Thailand in celebration of his 50th anniversary Valued at $4-12 million

25 Famous Finds Possibly the world’s most famous diamond
Valued at $250 million It has a long recorded history, dating back to the late 17th century. It has changed hands numerous times, from the kings of France to its home at the Smithsonian in the United States. Supposedly cursed 45.52 carats, about the size of a walnut or a pigeon egg Thought to be cursed because of the fate of its owners, in particular, Louis XVI, who was executed during the French Revolution. It was stolen at the end of his reign and during the intervening years it was transformed from the French Blue of the crown jewels to the Hope diamond we know today.

26 Famous Finds The Patiala necklace featured 2,930 diamonds, including the 428 carat De Beers diamond as its centerpiece. The necklace disappeared in 1948. When it was recovered 50 years later, the largest diamonds were missing. The Patiala Necklace was a necklace created by Cartier in 1928 for the Maharaja of Patiala. It contained 2,930 diamonds, including as its centerpiece, the world's seventh largest diamond, the 428 carat De Beers. The necklace disappeared around Part of it was recovered fifty years later with the De Beers diamond missing, along with many of the larger stones.

27 Recent News A flawless 59.6-carat pink diamond will be auctioned in Geneva this fall at a record asking price of $60 million dollars. The gem, which is known as the “Pink Star,” was mined by De Beers (a major mining conglomerate) in Africa in 1999. It received the highest possible color and clarity rating from the Gemological Institute of America (GIA). It weighed carats in the rough, and was cut and polished over a period of two years by Steinmetz Diamonds Pink diamonds of 5 carats are rare, this is unheard of! De Beers is a family of companies that does a lot of mining in Africa The same group that uncovered the previous record-breaking diamonds

28 Ruby Crystals formed by the mineral corundum (aluminum oxide)
Red color comes from the element chromium Color is the most important factor in determining a ruby’s value. After color come clarity, size and cut. Rutile (titanium dioxide) needle inclusions found in all natural rubies Can form a star pattern or reflect light in a special way, increasing the value of the ruby “pink sapphire” is basically a ruby Chromium is rare so rubies are special One of the most remarkable things about the formation of rubies is that geologists are not sure how it happens. The commonly held belief amongst geologists is that rubies are formed by tectonic plates smashing together – as did the India and Asia plates when the Himalayan mountains were formed around 50 million years ago – forcing limestone deposits deep into the earth where intense heat and pressure metamorphosed the limestone into sparkly marble. At the same time, molten granite bubbled up into the marble and removed the silica but left behind the aluminum through a process called metasomatism. The problem is, and the part that is confusing geologists, is that although the ruby-hosting marble extends over large areas of the Himalayas, the rubies themselves only appear in sporadic, localized patches. There must be some other missing piece of the puzzle that determines why and where rubies will form in this marble. This confusion was compounded by the discovery of some of the world’s most impressive rubies in the Mogok mine in Myanmar (formerly Burma). Whilst the rubies were hosted in marble, they were found alongside topaz and moonstone, minerals that are igneous rather than metamorphic in origin. This has confused geologists further and it may be many years before they find a final definitive explanation for how these beautiful gemstones are formed.

29 Ruby Myanmar region famous for rubies
Most rubies come from Asia and Africa. Rubies have also been found in Australia, Greenland, Brazil, and the US. The term “pigeon’s blood” is used to describe the rich, red color of Myanmar rubies (former Burma, so OK to call them Burmese rubies) US rubies found in MT, WY, and the Carolinas In Europe, Macedonia is the only place where rubies have been found Burmese rubies becoming scarce

30 Mining Gems Blasting Digging Dredging
You’ve got to look in the right place first, which depends on what you’re after Most gems are minerals deposited by water or volcanism Use the surrounding rock to indicate site and depth for digging, often in oldest parts of continental crust So… not Oregon, folks Modern tech like tractors and pneumatic feather and wedge drilling systems make it easier than shovels and mine carts Dredging is going through the rubble like panning for gold

31 A lot like mining for silver or gold
point out ventilation system

32 Ruby Rubies may be altered before they are used in jewelry.
Heat treatment improves color removes inclusions Repairing cracks lead glass used to fill fractures Heat degrees F To fill cracks: The ruby is dipped into oils, then covered with powder, embedded on a tile and placed in the oven where it is heated at around 900 °C (1600 °F) for one hour in an oxidizing atmosphere. The orange colored powder transforms upon heating into a transparent to yellow-colored paste, which fills all fractures. After cooling the color of the paste is fully transparent and dramatically improves the overall transparency of the ruby

33 Ruby Synthetic rubies can be produced. Used in red lasers
But if they are absolutely perfect then it’s obvious they aren’t natural rubies b/c all rubies have inclusions

34 Famous Rubies A ruby recently found in Greenland may be the world’s largest rough ruby. The crystal weighs 8.2 lbs. or 18,696 carats. Offered for sale by a company called 125West

35 Famous Rubies American billionaire Lily Safra’s ring, containing The Hope Ruby (a Burmese ruby of carats) was sold at auction in 2012 for $6,742,440. A ring belonging to Elizabeth Taylor which featured an 8.24 carat gem sold for $512,925 per carat (over $4.2 million in total) at an auction in 2011.

36 Star Rubies The Midnight Star 116.75 carats
Natural History Museum in NYC Today, out of every 100 rough corundum (ruby and sapphire) mined; only three will have stars apparent after being cut into cabochons. Out of these three, one will have a poor color but a good star; one will have a poor star but a good color and only one out of hundred will have both a good star and a good color! Most original sources of star rubies such as Mogok (Burma) & Vietnam have run out of supplies. Worldwide production today is yielding a very small quantity of fine stars (especially in sizes above 5 carats). Star rubies are becoming rare as most rough ruby today is cut into faceted stones after heating instead of being cut into cabochons to display the star. Stars called “asterisms” formed by rutile inclusions

37 Star Rubies Delong Star Ruby 100.32 carats
Natural History Museum in NYC In 1964 the Delong Star Ruby was the object of an infamous burglary, carried out by Jack Murphy, known as Murph the Surf, and two other men. It was then ransomed and recovered. The Delong Star was found at a designated drop off site - a phone booth in Florida.

38 Star Rubies Rosser Reeves Ruby 138.7 carats
Donated to the Smithsonian in 1965 He bought it and had it polished, which removed some material but re-centered the star and made it even more beautiful

39 Sapphire Crystals formed by the mineral corundum
Traces of titanium and iron produce the blue color. Other colors created by different chemical impurities Some corundum crystals used in watches, shatter resistant windows Also used as insulators in semiconductors

40 Sapphire Form as molten rock cools slowly beneath the Earth’s surface
Mined from primary sources (underground) or from alluvial deposits Most of the world’s sapphires come from Asia and Africa. Other major sapphire mining operations take place in Australia, Brazil, Greenland, and North America. Forms in coarse grained igneous rocks that do not have much silica In North America, Montana produces the most sapphires Madagascar produces a lot as well

41 Sapphire Sapphire is mined in much the same way as ruby.
It is treated prior to being used in jewelry. Diffusion treatments may enhance a sapphire’s color. Heat treatment as in rubies Yogo Montana sapphires may not require treatment, pristine and beautiful Diffusion treatment: Beryllium is diffused into a sapphire under very high heat, just below the melting point of the sapphire

42 Famous Sapphires Millennium Sapphire Discovered in Madagascar in 1995
The world’s largest sapphire, at 61,500 carats in weight

43 Famous Sapphires Logan sapphire 423-carats
National Museum of Natural History in Washington, D.C. One of the largest faceted blue sapphires in existence Surrounded in a diamond setting

44 Famous Sapphires The record price-per-carat for sapphire at auction was achieved by a sapphire from Kashmir in a ring, which sold for more than $175,000 per carat (more than $3.4 million in total) in May of 2013.

45 Star Sapphires Black Star of Queensland
The largest gem-quality star sapphire in the world 733 carats

46 Star Sapphires The Star of India 563.4 carats
Museum of Natural History in NYC

47 Star Sapphires The Star of Bombay 182-carats
National Museum of Natural History in Washington, D.C.

48 Emerald Emerald is formed by the mineral beryl with chromium or vanadium inclusions. Minerals dissolved in hot water beneath the Earth’s surface cool and slowly form crystals. Color and transparency are the most important attributes. BERYL = beryllium, aluminum, silicon, and oxygen Associated with pegmatite or calcite

49 Emerald Emeralds are found all over the world.
Columbia is by far the world's largest producer of emeralds. In the US, emeralds have been found in Montana, Nevada, Connecticut, and the Carolinas. More recently, emeralds have been found in the Yukon. 90-95% from Columbia

50 Emerald Mining Mining is done in two ways: a process called open pit mining (which is not used very often due to environmental problems), and the other process is through tunneling following the white calcite veins with possible emerald crystallization. Gem mining is very difficult, but Emerald mining is even more difficult because contrary to others, which are also found in the river beds, emeralds are found only in their original growth pockets. Open pit mining produces tailings / slurry that can be harmful to the environment Or erosion concerns Water pollution can be a concern Sometimes when they are finished mining, the land is converted to a landfill

51 Emerald Emeralds are often enhanced before sale by adding oils which improve their luster. Need to disclose report of any enhancements made

52 Famous Emeralds Patricia Emerald Found in Colombia in 1920 632 carats
Special because the crystal is 12-sided   Named after owner’s daughter

53 Famous Emeralds Gachala Emerald found in 1967 in Colombia 858 carats
now at the Smithsonian

54 Famous Emeralds Duke of Devonshire Emerald Discovered in Columbia
Presented to the duke of Devonshire in 1831 carats

55 Famous Emeralds Teodora emerald
This 57,500 carat stone may be the world's largest cut emerald. Up for auction, expected to bring a price of $1.15 million Originally found in Brazil Cut in India Bought by Reagan Reaney in Calgary, BC who is auctioning it There are doubts as to how much of it is real emerald If it doesn’t sell, it will be donated to Gemological Institute

56 Famous Emeralds Bahia emerald
At 840 lbs., the largest single emerald crystal ever found Valued at $400 million First discovered in Brazil in 2001 Found in a storage basement in New Orleans after Hurricane Katrina Reported stolen in 2008 from a secured vault near Los Angeles At one point, it was listed on eBay with a Buy it Now price of $75 million! Several competing claims of ownership Eventually, the emerald was taken into the custody by the Los Angeles Sheriff's Department. The case will be decided in court in 2013. It’s like 1.9 million carats

57 Famous Emeralds Chalk Emerald Columbian emerald 37.82 carats
Belonged to a noblewoman in India In the 20th century, the emerald was recut and set in a ring designed by Harry Winston Inc. The Chalk family donated it to the Smithsonian in 1972. Surrounded by 60 diamonds totaling 15 carats

58 Famous Emeralds Mogul emerald 217 Carats Originally from Columbia
Cut and sold in India to a Mogul noble Engravings date back to late 1600’s Sold at an auction in 2001 for over $2 million Now in a museum in Qatar

59 Famous Emeralds Imperial Emerald 206 carats
Amazing color and transparency, completely unenhanced Being offered for sale by New York company Bayco Jewels at the gem exhibition in Switzerland this year

60 Pearl Calcium carbonate deposits formed by shellfish
Found in freshwater and marine environments around the world Japanese pearls, Indonesian South Sea pearls, and Tahitian pearls are the most famous.

61 Pearl Pearls may be natural, farmed, or imitation.
Of these, natural pearls are the rarest Perfectly round and shiny pearls are the most desirable. Colors may vary from white or cream to yellow, pink, or black. The color of pearls is determined partly by chemistry and environmental factors, but primarily by the species of mollusk that produced it (the pearl being the same color as the mollusk’s mantle). Black pearls used to be rare, but now they are being farmed, so one color is not necessarily more valuable than others. Real pearls can be dissolved by acid X-rays show layers of development in real pearls Plastic ones are perfectly smooth and round, real ones have a slightly gritty surface In addition to being used in jewelry, pearls have also been used in cosmetics and in paint

62 Harvesting Pearls

63 Famous Pearls The Pearl of Lao Tzu (also known as The Pearl of Allah) is the largest known pearl. Recovered from a giant clam in the Philippines in 1934 The pearl is 9.4 inches in diameter and weighs about 14 lbs. this pearl is valued at $3.5 million due to its astounding size

64 Famous Pearls Other famous pearls include necklaces worn by royalty.
Rare necklaces have sold at auction for $1-3 million. A necklace worn by the Baroda nobility of India sold for over $7 million. Known as the gem of queens Hard to find natural pearls of matched size, which is one reason why whole necklaces of natural pearls are valuable Also adds value if it was worn by someone famous


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