M I N E R A L L O G Y

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Introduction to minerallogy and diamonds

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  • M I N E R A L L O G Y

    1. 1. MINERALOGY
    2. 2. MINERALOGY <ul><li>Mohs’ Scale of Hardness </li></ul><ul><li>In 1812 the ‘Mohs scale of mineral hardness’ was devised by the German mineralogist Frederich Mohs (1773-1839), who selected the ten minerals because they were common or readily available. The scale is not a linear scale, but somewhat arbitrary. </li></ul>
    3. 3. The 10 common minerals arranged in order of hardness <ul><li>1 Talc </li></ul><ul><li>2 Gypsum </li></ul><ul><li>3 Calcite </li></ul><ul><li>4 Fluorite </li></ul><ul><li>5 Apatite </li></ul><ul><li>6 Orthoclase </li></ul><ul><li>7 Quartz  </li></ul><ul><li>8 Topaz </li></ul><ul><li>9 Corundum Sapphire and ruby are varieties of corundum. </li></ul><ul><li>10 Diamond </li></ul><ul><li>2.5 Fingernail 2.5–3 Gold, Silver 3, Copper penny 4-4.5, Platinum 4-5, Iron 5.5, Knife blade6-7, Glass 6.5, 7+ Hardened steel file </li></ul>
    4. 4. The Cullinan Diamond <ul><li>This 3,106 carat diamond is the largest gem diamond ever found. It was discovered in 1905 at the Premier mines in South Africa by Frederick Wells, a mine superintendent. He was walking through the mine at the end of the day, when he happened to glance up. He noticed a large mass in one side of the mine wall. Thinking it was a big piece of glass embedded by a practical joker he examined what turned out to be a huge diamond. Wells received $10,000 for his find. The diamond was named Cullinan, after the mine's owner Sir Thomas Cullinan. Weight: 3,106 carat (rough) Cut: Final cut Pear shaped diamond </li></ul>
    5. 6. Doesn’t look impressive!
    6. 7. Cutting the world’s biggest diamond <ul><li>It was purchased for $800,000 as a present for King Edward VII for his 66th birthday. The stone was sent to the Asscher Brothers in Amsterdam to be cut. They had successfully cut the Excelsior, previously the largest diamond. The huge uncut stone was studied for months. Then on February 10, 1908, Mr. Asscher stuck the steel cleaver's blade to make the first cut. The blade broke while the diamond remained intact. </li></ul>
    7. 8. Panic? <ul><li>On the second attempt, it split exactly as planned. It was reported that after the second cut, Mr. Asscher fainted. Further cuts produced three principal parts, and these in tern were cut into 9 major gems, 96 smaller brilliants, and 9.5 carats of unpolished pieces.The Cullinan I was the largest gem produced from the rough stone. It is a pear shaped stone of 530.2 carats and is the world's largest cut diamond. The Cullinan I is now in the head of the royal scepter in the British crown jewels. The second largest cut diamond, the Cullinan II, is a cushion-shaped stone weighing 317.4 carats, and is set in the British imperial state crown. </li></ul>
    8. 9. The Cullinan cut up
    9. 10. CARATS <ul><li>Caratage means CARAT , the measurement used to weigh a diamond. One Carat= 200 milligrams, or 0.2 grams. 142 carats adds up to one ounce. Carats are further divided into points. The price of a diamond will constantly rise proportionately to the size of the stone. The larger diamonds are very rare and have a greater value per carat. For example when discussing points, remember that a one-carat diamond will cost much more than a 95 pointer. The word carat is taken from the perfectly matched carob seeds that were once used in ancient times to balance scales by merchants. </li></ul>
    10. 11. The Star of Africa
    11. 12. The Star of Africa
    12. 13. The Cullinan 1 (Star of Africa) in the sceptre (crown jewels)
    13. 14. Cullinan 2
    14. 15. Imperial State Crown

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