March 20 - -Color: Colorless generally preferred Rubies and...

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GEMS Diamonds - Composed of carbon - Hardest substance known - First found in RIVER sediment in India, later Brazil - Found in Orange River near Hometown, South Africa-1866 - But what is the ultimate source of diamonds? Cecil Rhodes - Founder of DeBeers Origin of Diamonds - Found in the igneous rock, kimberlite - Kimberlite occurs in pipe- or funnel-shaped bodies - Kimberlite (and diamonds) come from Earth’s mantle Cullinan Diamond (1905) Uses for Diamonds - Abrasives (polishers) – most common use - Gems Value of Diamonds (4 C’s) - Carat: 1/142 ounce or 1/5 gram - Cut: Quality of shape and polish o Brilliant cut has 58 facets and is the most common - Clarity: Flawless means no imperfections when viewed with 10x lens
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Unformatted text preview: -Color: Colorless generally preferred Rubies and Sapphires-Gem variety of the common mineral Corundum (Al203)-Found mostly in metamorphic rocks where the original rock had a high alumina content Emerald-Emerald is the gem variety of Beryl (more valuable than diamonds or gold)-Origin: Usually found in igneous rocks (granites), but also in hydrothermal veins-The finest come from Columbia Time for a Gem Test a. William Ralston (president of San Francisco bay in late 1800s) and Clarence King (geologist) surveying the site along to route to transcontinental railroad...
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This note was uploaded on 09/09/2009 for the course GEO 301 taught by Professor Long during the Spring '07 term at University of Texas at Austin.

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March 20 - -Color: Colorless generally preferred Rubies and...

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