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Gemstones of IgneousHydrothermal Origin
Gemstones Formed by Very High Temperatures and Pressures
Gemstones Formed at Groat Depths
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alluvial amethyst Angeles County aquamarine Argyle Diamond Argyle pipe basalts beryl Bo Rai Bonatti boulders Brazil Burmese carats Ceylon Chanthaburi Chanthaburi-Trat Chhibber Chivor collection Colombia Coober Pedy corundum crust crystals depth dikes district eral Erica Van Pelt feldspar Figure formation fractures gem deposits gem gravels gem-bearing Gems & Gemology gemstones Gemstones Formed Geol geology Giibelin gneisses granitic Gubelin Harold and Erica hydrothermal important India jade jadeite Keller Khao Ploi Waen kimberlite lamproite limestone located magma mantle meters Minas Gerais mining activity Mintabie Mogok Mogok area Mogok Stone Tract Muzo Natural History Museum occurs opal opal deposits opal field pegmatites peridot peridotite Photo by Harold Photo by Peter placer precious opal produced quartz rare Red Sea regional metamorphism rocks sandstones sapphires schists sediments silica Sinkankas Smithsonian South Australia South Wales spinel Sri Lanka Tawmaw Thailand thick topaz tourmaline veins weathered world's finest Zabargad Island zone