Natural TreasuresNatural Treasures

Precious MetalsPrecious Metals

• Naturally occurring

• Metallic elements

• Rare

• Valuable

Precious MetalsPrecious Metals

• Graded on:– Rarity– Purity– Mass

Precious MetalsPrecious Metals

• Silver: current value $22.38 per ounce

• Gold: current value $1323.39 per ounce

SilverSilver

• 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.

GoldGold• 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.

Gold Rush!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.

Famous FindsFamous Finds• Holtermann Nugget

– found by Bernhardt Holtermann in Australia in 1872

– weighed in at just under 640 lbs.

Famous FindsFamous Finds• Welcome Stranger

– found by John Deason and Richard Oates in Australia in 1869

– weighing in at 2316 troy ounces (about 159 lbs.)

Famous FindsFamous Finds• Hand of Faith

– found by Kevin Hiller in Australia in 1980

– 876 troy ounces (almost 62 lbs.)

MiningMining

• Sluicing

• Dredging

• Hard-rock mining

ProcessingProcessing

• 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.

ProcessingProcessing

• 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.

Precious GemsPrecious Gems

• Pretty minerals used to make jewelry

• Graded based on – Color– Cut– Clarity – Carats (size)

Precious GemsPrecious Gems

• Precious gemstones– Diamond– Ruby– Emerald– Sapphire

DiamondDiamond

• 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

DiamondDiamond

• Primary source: brought up by volcanic activity

• Secondary source: dispersed by erosion

Diamond MiningDiamond Mining

• 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.

Diamond MiningDiamond 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.

• http://dsc.discovery.com/tv-shows/dirty-jobs/videos/outback-treasure-hunter.htm

Diamond MiningDiamond Mining

• Blood diamonds

DiamondDiamond

• Color in diamonds comes from impurities.– Nitrogen is the most common and creates the yellow

and brown color of most diamonds.• Synthetic diamonds • Almost diamonds

Famous FindsFamous Finds

• The Cullinan diamond is the largest gem-quality diamond ever found, at 3106.75 carat (about 1.37 lb.) rough weight.

• It was found in South Africa in 1905.

Famous FindsFamous Finds

• The Golden Jubilee is the largest faceted diamond in the world.

• At 545.67 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.

Famous FindsFamous 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

Famous FindsFamous 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.

Recent NewsRecent 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.

RubyRuby

• 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.

RubyRuby

• Myanmar region famous for rubies

• Most rubies come from Asia and Africa.

• Rubies have also been found in Australia, Greenland, Brazil, and the US.

Mining GemsMining Gems

• Blasting

• Digging

• Dredging

RubyRuby

• Rubies may be altered before they are used in jewelry.

• Heat treatment – improves color– removes inclusions

• Repairing cracks– lead glass used to fill fractures

RubyRuby

• Synthetic rubies can be produced.

• Used in red lasers

Famous RubiesFamous 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.

Famous RubiesFamous Rubies• American billionaire Lily Safra’s ring,

containing The Hope Ruby (a Burmese ruby of 32.08 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.

Star RubiesStar Rubies

• The Midnight Star

• 116.75 carats

• Natural History Museum in NYC

Star RubiesStar Rubies

• Delong Star Ruby• 100.32 carats• Natural History

Museum in NYC

Star RubiesStar Rubies

• Rosser Reeves Ruby• 138.7 carats• Donated to the

Smithsonian in 1965

SapphireSapphire

• Crystals formed by the mineral corundum • Traces of titanium and iron produce the blue color. • Other colors created by different chemical impurities

SapphireSapphire

• 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.

SapphireSapphire

• 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.

Famous SapphiresFamous Sapphires

• Millennium Sapphire

• Discovered in Madagascar in 1995

• The world’s largest sapphire, at 61,500 carats in weight

Famous SapphiresFamous Sapphires

• Logan sapphire

• 423-carats

• National Museum of Natural History in Washington, D.C.

• One of the largest faceted blue sapphires in existence

Famous SapphiresFamous 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.

Star SapphiresStar Sapphires

• Black Star of Queensland

• The largest gem-quality star sapphire in the world

• 733 carats

Star SapphiresStar Sapphires

• The Star of India• 563.4 carats• Museum of Natural

History in NYC

Star SapphiresStar Sapphires

• The Star of Bombay

• 182-carats

• National Museum of Natural History in Washington, D.C.

EmeraldEmerald

• 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.

EmeraldEmerald

• 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.

Emerald MiningEmerald Mining

EmeraldEmerald

• Emeralds are often enhanced before sale by adding oils which improve their luster.

Famous EmeraldsFamous Emeralds

• Patricia Emerald

• Found in Colombia in 1920

• 632 carats

• Special because the crystal is 12-sided  

Famous EmeraldsFamous Emeralds

• Gachala Emerald

• found in 1967 in Colombia

• 858 carats

• now at the Smithsonian

Famous EmeraldsFamous Emeralds

• Duke of Devonshire Emerald

• Discovered in Columbia

• Presented to the duke of Devonshire in 1831

• 1383.95 carats

Famous EmeraldsFamous 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

Famous EmeraldsFamous 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.

Famous EmeraldsFamous 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.

Famous EmeraldsFamous 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

Famous EmeraldsFamous 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

PearlPearl

• 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.

PearlPearl

• 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.

Harvesting PearlsHarvesting Pearls

Famous PearlsFamous 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

Famous PearlsFamous 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.